I have had the best luck with bras that a silicone lining around the top of the cup. Both Wacoal and Itty Bitty Bra have great ones. The silicone helps to keep the bra from sliding down to your hips. Also, try to steer away from bras with too much padding. Again, the padding seems to pull down when you have less “cup” to hold it up. Since you are a smaller cup size, I would forego the strapless bra altogether and use the silicone nipple covers. They stick to you, don’t fall off (even in hot and humid climates), cover the essential parts, and you don’t have to worry about tugging at a strapless bra. Brands like Hollywood Fashion Tape, Commando, and Miss Oops make them and they are all great.