I'm going to be the black sheep here. You need at least ONE black sheep!
I smoke weed, and I have never seen anything wrong with it. It's not something you do EVERY DAY, it won't impact your grades AT ALL. (I'm getting nearly all As, at the moment).
The key lies in moderation, if you do it all the time, it WILL impact your life; if you just do it when you feel like it, when you go out or when you're really stressed, it's more than fine. It's just like alcohol, you wouldn't drink every day. And, actually, it doesn't have all the aggressive side to it that alcohol has.
What it does do, is relax you, make you happy and dumb and giggly and weird and hungry for a while, and then pass.

I'm not saying you should do it. If you don't want to, you shouldn't. I understand you want to feel more confident and relaxed, I feel the same. I'm a jittery thing, nervous, tense, always in control, and I hate it. But, a thing I've learned is that if you're not comfortable in the first place, weed might just make it worse. If you decide to try it, make sure you're ALREADY feeling ok, don't do it TO feel ok, because it won't help, at all.
So there, this isn't some moralistic reason to not do it, but an actual, tested-on-myself sad, sad fact. If you're gonna smoke to feel better in a situation where you don't feel ok, it's not gonna work. If that is your only reason to, don't, because it'll make you a bazillion times more anxious and make you close yourself in your head.
What I am saying,though, is that it really doesn't deserve the stigma, it's nothing like hard drugs, it's something that may very well be legalized instead of alcohol, which is a much meaner thing.