Im 59, 120lbs & I am a G-Cup...with that said, the medium fit pretty well.  It looked awesome on, I must say that.  Also, it didn't dig in anywhere to suggest any fat bulging anywhere.  I just had to be careful of a nip slip, (to be fair & I kno this is TMI, my areolas aren't tiny...theyre not huge, but they're approx the size of a silver dollar?) I was able to wear this without any nip slips though, which was great.  I wouldve ordered the large though to allow for more cleavage because I couldn't adjust my boobs cuz I had to cover my nips w/ the fabric.   I recently went from 108-120, (but, Im 59, so I have to accept that) but Im just used to wearing XS/S.  Had I gotten the large, I prob wouldve been able to show off my curves/body more because the material is very stretchy, so its going to be tight no matter what size you order.