Sorry for length, I need to start writing to the forum on my IPad instead of IPhone so I am aware of how long my posts are. (Edited for this paragraph). 
@Liqidluv
Are you sure it’s your pelvic bones and not your second sphincter? If you’re taking 2.1 inches wide and stopping around 9 inches in (variable by anatomy of course), it may be your second sphincter that’s stopping you.
If you feel like you have hit a wall with a deep ache. It’s because you have. It’s the second sphincter that blocks direct access to your intestines.
I have a 15 inch by 2 and 5/8 inch wide (not circumference) that I couldn’t get in for ages until I researched this issue and asked a lot of my gay friends for advice.
Arguably it could be your pelvic bones if you’re really petite framed, which I’ve never heard of being an actual cause , but it’s possible I guess.
I know men who take 20+ inch Bad Dragons (which are I assure you, are huge both in length and width), with ease. They all had to pass this “hurdle,” and it’s always related to “popping the second sphincter.”
Think of it this second sphincter, like a woman’s cervix. You have to breach it with something narrow then work the opening wider over time. Otherwise, you’ll most often put the woman in intense pain.
If you’ve ever busted a woman’s cervix you’ll know what I’m talking about. It’s that stretchy resistance that feels good for the man, especially when the man breaches it because it’s literally a second “ring” of resistance you can feel yourself thrusting in and out of.
This sometimes does and sometimes doesn’t feel good for the woman though. It all varies by person and anatomy.
I’ve had more than one woman who loved it.
More than one who threw up from the pain even though I warned them and went really slow.
And some that immediately said stop and almost threw up.
(And unfortunately, I’ve had to take a few women to the ER who thought they were enjoying it in the moment, until the cramping started afterwards and they thought they couldn’t walk or stand up.)
If I were you, I would look into more “skinny angle tipped ‘flexible/soft’ length toys,” to break this barrier if you determine it’s the case.
A big “firm/hard” dildo won’t pop through it, I can almost assure you. Unless you just brute force it which I’m relatively sure you won’t enjoy and pretty positive you won’t be able to tolerate doing that by yourself.
@JoCat
Me neither. Many of my gay friends or TS (please don’t blast me on the terminology, this is their chosen term of reference and it does vary from person to person), friends with huge penises, have flat out told me they ended up going the route they went because no woman would have sex with them due to their size.
But men would. And have longer torsos (typically speaking, not always), which makes the depth of the inner sphincter much deeper when a 6’+ man’s torso versus a 5’ woman’s torso length.
However. That being said both men and women possess this same second sphincter. There are some amazing anal size enthusiasts as women who are out there and I’ve asked them and they have experienced the same thing with the second sphincter.
I’m not arguing that what others have said about the pelvis in men and women isn’t potentially true, and from an anatomical perspective women’s hips are wider, much wider in some cases (especially after child birth).
But I’ve never heard of this being the reason, but DO know from personal experience that my issue was the second sphincter, and only found this out by talking to a lot of my friends who flat told me what the issue was the second I asked and also advised me how to “get through it.”
I will state from experience though, that if this is determined to be the case. Take the slow route with patience, and don’t try to rush it like I did or you will find yourself out of commission for a while. 
