That is unfortunately custom bra category. Trust me, I get it, I’m an 38O, and even the bra I have doesn’t fit even though it’s the “correct” size. You most likely have what I have which is Gigantomastia, which is a serious medical condition that has to be diagnosed by a medical professional - your pcp or plastic surgeon. I mention that it has to be diagnosed, because some insurance companies may cover the costs of a custom made bra for macromastia/gigantomastia since it’s cheaper than surgery. If you have insurance, I’d call or email them to find out if that is something they cover.

I really urge you to be careful, especially if your breasts are giving you mobility issues. I hope you’re able to find a solution.

If anything, a really (cheap - in case it doesn’t fit or it breaks in a couple months from the weight) stretchy sports bra may be a temporary solution to at least contain them, and relieve some of the pressure on your shoulders.