I am a size 34 B, breastfeeding mama, and I got the size Large because I wanted more actual coverage fabric-wise than the medium. You can tie it tighter but this does not have loads of support. I would say this is great for the beach and relaxing but might not the suitable for activities. I’ve had some boob “spilling” lol. It is more supportive than the twist tie top. It is very flattering and I purchased it in two colors, white, and blue shells from studio makawao.