Guys, gals, and nonbinary pals, i need recommendations

Im genderfluid, and an amab twink, but i tend to lean more towards femme, but ive only tucked with biking shorts, which kinda work until i sit/lean down, but thats not the main concern atm, i need help finding a good bra/fake breasts that i can hide semi easily, my mom knows im trans, my brother just got top surgery, but its my cousin im worried abt, my little cousin in which i share a room with is fine with my brother, but calls me slurs, and is constantly just trans/homophobic towards me, and i dont want to hear him go off if he sees them in my room, so basically, instead of like, a tank top style fakies, id rather have individual ones, that i can hide easier, or just really padded bras, i have a mannequin that i style my outfits on, and hers seem to be like a D cup, and i dont know what my band size is, but i can find that out later, im also on a pretty tight budget, but anything good and somewhat cheap will help