Help from teenage girls PLEASE?

ok so im 14 and i no this girl whos a grade above me and people have told me that she likes me and i have liked her as long as i can remember but i dont want ti ask her out cause we are 14 i want to wait till we are older and i can drive(plus if we date now cgances are we will break up by our junior year. i really like this girl i want to marry her) but i dont just want to shut her down and then she wont like me in a few years. what should i do? should i explain my "idea"(execpt for the marrige part. i dont wanna creep her out) to her like i just did to you or what. if someone could even give me their email so i can get more help from you that would be great. and by the way our families are friends so i see her pretty often. please help! thanks