I also have some sensory issues with clothing, so I totally get where you’re coming from! Ordering something online without knowing the material can be a nightmare.
I posted in the recent purchases thread about some teddies I was buying, and I’ve been wearing them to write reviews.
Think I can safely say that two out of three could possibly be suitable for your requirements.
This teddy is super soft, and the straps down the back aren’t even noticeable on my skin, I don’t feel them at all, and the waistband can be loosened or tightened as you’d like. I’ve been wearing this one to bed because it’s so soft.
And this teddy could also be suitable, depending on how your sensory issues are with satin (I know it’s a hit or miss for a lot of people). Very soft, flowy material, and the straps are also fully adjustable. The only thing you can’t adjust is the waistband, as it’s elasticised.
Hope you find what you’re after! 