Well AI plays sg a 6'0 and most say he's actually shorter. If you get really fast, strong, and develop a good jump shot you can play sg. But I would suggest just working on being a pg, maybe even a combo guard which would make you more valuable.

Im assuming you're a sophomore? You got another year until you really want colleges to look at you. Just keep working on it. You can also still grow a little, but I think 6'4 is out of reach to be honest. You can try some of those stretches.