I am 120 lbs and a 34B. The S/M that I ordered was actually just a M, and it was too small in the cup area. Taking out the padding helped, but a L would have probably been a better fit (I’ve never been a L in my life).
I agree with other reviews that the band and stitching feels a little cheaper than the rest of the material, but overall it looks great. I love the open back, and the straps stay in place.