I'm 5'3 and about 140 lbs. 34C and size 6 jeans. I got the size medium and it fits perfect! The straps are adjustable if needed and the material does have some stretch to it. This honestly was a lot better than I expected.
Wore it for a photoshoot and LOVED this one piece! It's comfortable, movable, sheer in the back but has coverage from the lace in the front. I usually wear an L, (13 pants and a 38D), so I would order true to size on this!