Confidence comes with age and experience too, bro. Try not to stress so much about it. I'm only a couple years older than you and I've just become more and more confident over the past few years. 21 is a tough age because you're still in school and aren't totally established yet and you're anxious to do so. Just enjoy being in school, go out with your friends, and talk to anyone and everyone. As far as ladies are concerned, talk to them...some will shut you down, some won't. It happens to every guy. You never know unless you try. Like I've said, just have fun! You don't want to turn to any form of drug for an ego boost.....