Lily, try walking on the treadmill on a steep incline slowly to simulate lunges. Hold onto the side rails
Lunges and heavy squats will eventually give you a high "bubble butt".
I have the same problems with bras, made even more exasperating because I deliberately lift to widen my back. Very heavy chest presses have given me big pectoral muscles (what your boobs hangs from) so that fills a little. What worked best was spending several
hours in Victorias Secret with a sympathetic (not 19 yr old) saleswoman who had me try on just about every style without rhinestones or leopard print
We eventually found two or three styles that fit, felt good, and I felt good wearing them. Expensive, but I did manage to find some of then on sale during their July sales. Hurry!
Mel