Go for it! Life is short believe it or not and like you said, you are still in high school. Yes he could say no, but if he does I think you already see its not rhat huge of a deal, atleast you wont go forever thinking if id made the move maybe it wouldve worked, he couldve been my future husband (maybe a bit dramatic there) however, you get my point.
You have to take chances in life, or you will never kniw what can happen. Are you not going to apply for a job one day because you MAY get turned down? I certaintly hope not. Dont let life pass you by, go for it, besides the guy asking the girl all the time is cliche. He may love the idea of a girl asking him :) let your nerves go, be creative, assert yourself and go for it! Ill be here for advice or to just talk if you need it!
My brother met his wife before he left for basic training. A little while later, when he was home for a visit, they ran into each other and they hit it off. They've been married now for almost 20 years. I think if you are meant to be together, then the universe will make it happen.