It’s so bad that my fiancée has some bras that say she’s a B cup and others that says she’s a D cup. In order to go bra shopping, you have to actually try them on to find out if they fit.
If I had to try on underwear to see if they fit, I might not bother with underwear at all!
Oh believe me, I fully get that I have a bit of “small boob privilege” in terms of being able to wear bralettes. Do the non-bralette, non-underwire bras still not work for you though? They seem to provide a decent amount of support, but idk how they work for everyone.