As far as I know, you cannot pick a different size between the tops and bottoms. I carry more weight in my upper body than in my lower body and the bottoms don't fit me. I haven't gone swimming in the suit yet, but I know with how loose the bottoms are, they would come off. I like the top so much that I'm not going to return it. I should contract the seller and see if there's anything that can be done, but haven't yet.See full review