that's what i do. i hate the "mono-boob" that sports bras give you by themselves. they do make sports bras that have an underwire, and those are okay too. and wearing 2 bras gives you more support, especially if you have larger boobs.
Well don't ask her per say. just initiate things. like say if you guys were like making out...try maybe trying to unzip her pants or touching her.
if she pulls away or doesn't seem to want it then just drop it. she probably won't get mad. but also let her know that you feel like you guys are...