Hmmm I’ve finally just tried this and apparently I’m an E or and F… I find that difficult to believe as I normally wear a C!
Happy to test the theory though, now where is the best place to buy a bra from? 
I’m thinking practical tshirt bra or something to start with…
Bras… argh!
It is no better for small breasted women either.
It isn’t just bandwidth / cup size which never stays the same, it is the fit according to style etc.
My personal gripe is that well known department stores seem to think that small boobs are closer together. Cups ought to have some sort of slider to move them further apart or nearer to each other… some Lovehoney lingerie has sliders.
Also hate underwiring unless it is bedroom wear - like a basque.
All I can suggest is finding a brand and a style which suits, and sticking with it - a bit boring, but for days when I want to wear a bra I found an online company selling plain, black, non-underwired bras (other colours are available) which I pair with black Flirty knickers from Lovehoney. The bras are Japanese - without meaning to stereotype I think the company has a better understanding of a slighter physique that a lot of UK department stores.
Bedroom-wise, plunge bras are hopeless on me but balcony styles work, even though there is not much to support - they seem to reach round to better cover side-boob…
When I ditch the bra I wear one of these Mapale Bodies. I have a couple - perfect day or night!
I’m currently wearing a 34 GG so I was astounded to see the size 40 H pop up! I knew that my bras aren’t the best the fitting and they are getting on a bit too. I must have put on a bit more weight than I realised! 
I can go with a fair bit of overspill if it’s in bedroom lingerie but not for everyday wear under clothes. It’s very difficult to hunt down a well structured , underwired one that’s pretty and in nice colours when you get past a G cup! And then, of course they cost a fortune too!
Another factor is the amount of stretch in some bras, if there’s too much after a few weeks you find that you’re left with zero support because the weight of heavy breasts has stretched the bra to its fullest and you start continually tightening up the straps in an attempt to gain some kind of control . This never works as the main support should come from the body of the bra itself, not the straps.
Honestly I could go on and on about this , it’s been a problem for me for about as long as I can remember !
As an adult I’ve been between a DD and an J cup and between a 32 and a 40 back…due to weight yo-yoing
Have to buy really expensive bikinis to support my boobs…
No brand is the same as another and it’s really no fun bra shopping at all…
Grrrrrrr
@wildflower & @CurvyJilly sounds like a nightmare.
My issue is getting enough shape under clothing, but I can see that getting enough support is important too.
It shouldn’t have to come from the shoulder straps - that is a recipe for back pain.
It should come from under boob bandwidth and side build of the bra (does that make sense?).
I think bra shopping is like jeans shopping - a nightmare, and a relief when you find your make and fit - stock up. And these are staple items of clothing!!
Good luck to you both!
My better half has totally given up on conventional bras.
Whichever size she’d wear, she always had some marks around her chest. She’d come home and couldn’t wait to take them off.
In the end, she has gone for yoga type bras - comfy every time, every day - and usually ou’re cotton, so reasonnably eco friendly.
Perhaps not the prettiest, but a plus point is that it’s easy to slide your hand in from the top to hold her boobie whilst watching tv… 
I should point out that she is reasonnably small breasted cup a to b. No idea how thay impacts on support and sports/yoga bras.
Brilliant bra calculator @Lovehoney_Brenna 30E / 32DD as I had previously thought. I did giggle imagining all us ladies (people who wear bras) lying down, craning necks to see the measuring tape (while I was doing exactly that)
Thank you sharing for this - apparently I’m a 32E rather than a 32DD…
I was a bit dubious as to how much difference it would really make but after trying the different cup size I think it does - my boobies are much happier!
Ooh great to hear, I’ve found out that amazon does “prime wardrobe” where you order 6 items for free and send it back if you don’t want it and you only pay after 7 days when you decide what to keep (if anything) I don’t know if I’d use it for much, but its a great idea for bra testing!
Looking forward to getting my many varying bra sizes to try on haha
@Sooze86 that’s a good idea - I’m going to have a look tomorrow.
I tried the @Lovehoney_Brenna bra sizer too - very good and very flattering but I know I am not a 32C (sigh). I’ve stopped letting (lack of) boob size get to me - we are what we are. I know size helps with fitting, but after that let’s just find ways of enjoying our own unique shapes.
I’ve posted pics of myself on the photo thread recently and I am very pleased with the results, despite the lack of curves. It has been a confidence boost and MrR has been fully supportive - I can now see what he sees.
Every shape has beauty. The days of other people saying that I am too thin to wear xyz are over (not that I ever took much notice, but people can make undermining comments - I’m more likely to challenge them, now, rather than take it to heart).
Okay so my bra’s arrived today, I went for all the same so that itd be easy to judge, I went for 38C that I currently wear, 38D and 38E and 38F.
@Lovehoney_Brenna’s recommended site said I was E or F… But no, I don’t know much but “sad deflated boob puddle in a giants hat” was not the boob vision I was looking for
D and C seemed to fit okay, but there was such a lot of armpit flaboob going on I can’t say they looked or felt right either.
Back to the drawing board, can’t work on feeling attractive if I can’t even find a boob holder. 1/10 much dissapoint.
Aww @Sooze86 I am only use to taking them off so I have limited knowledge of bras hun sorry I can’t be any help gl
Oh no @Sooze86! That’s such a disappointment isn’t it. One of the most frustrating things is that different stores seem to size differently.
I just wanted to check you do the “scoop and swoop” when putting on a bra? It makes a massive difference to that under armpit boobage!
That’s very frustrating @Sooze86 If you’re anything like me then you build your hopes up that at least one will fit!
Until I started reading this thread I didn’t realise armpit flab/boob was a common thing , I thought it was just me! Good bit of advice there from @SexInTheCity as regards scoop and swoop, I also lean forward and kind of let the boobs fall naturally into the bra before doing it up .
Hope you have more luck finding the right bra soon 
Sorry you were disappointed @Sooze86.
When yo find the right one, buy a few! I do this with bras and jeans… Once you find the right brand for you, you’ll be fine.
I feel your pain when it comes to bra shopping, I’m a big busted lady and do struggle. I find that some shape bras suit me better than others, I can find balconette bras quite easily but struggle to find plunge bras that fit well. It’s all trial and error when it comes to styles. I tend to stick with a well known high street store beginning with B ( not sure if we can name stores here) their fitting service is great and their assistants really knowledgeable. They always make sure everything fits perfectly and will always let me know if a style suits me or not.
@PaintedLady84 so glad you have found your style and your shop.
You are right, we can’t name competitors here
I think quite a few folk find push-up plunge styles tricky - in pushing boobs closer together I think they miss the sides and then the underwires dig in to soft tissue. I prefer balconettes too, and I’m tiny! The cups just seem to stretch further around.
There is a rib - I think it is a rib, maybe where they join together - just under the arm and next to each breast (it feels like a vertical line)- In my experience the cups of the most comfortable bras (they can still be sexy!) cover that.
You’re absolutely right about them still being sexy, in the last few years especially stores and designers have realised that we dont just want functional material to hold the girls in, we also want pretty or sexy styles that make us feel good.
I’m particularly noticing that as a woman with more than her share! Previously all that was ever available was the full cup (I used to call them grandma bras) from department stores. Now there is such a huge range out there and I dont struggle as much to find something to make me feel good.
@PaintedLady84 that reminds me of a time in a department store changing room
I saw an assistant marching towards a cubicle with an armful of white nylon ‘granny bras’. A few minutes later the occupant exclaimed, loudly, ‘I’m not bloody wearing those - he’s on his way back from Afghanistan!’.