I'm 5'7", 115 and I got a M/L because I have long legs and a full chest. The tag said medium when I got the dress, FYI. Dress fits perfectly and gives me room to move in. Has padding so a bra isn't completely necessary, but it's a little see through so white underwear is definitely necessary. It got here like 12 days after I placed my order so I would definitely recommend it!!