Honestly, I'd take the pressure off and not plan to ask her out. You're getting an extreme reaction to a completely innocuous situation, she's just a girl, might be hot, but you gotta deal with some things, if you're puking out of nervousness the pressure of a relationship ain't gonna be much help. Tbh, if you're spendin this much time together she probably likes you back. You realise even if she's not interested its not the end of the world, and it really doesn't mean nothing about you, you know how many girls have turned me down? Bout 1 for every 4 doesn't, that's a 25% success rate, get some thick skin son and take it easy on yourself.