She's a senior, I'm a freshman?

So there's this girl. She's going to be a senior next year and I'm going to be a freshman. I started hanging out with her and her friends in November of this year. I feel like we're really close friends. I've never really addressed the possibility that I'm some little kid to her, but I feel like she doesn't think of me that way. We hang out at least 3-4 times a week currently. It waxes and wanes, but for the most part it's pretty consistent. Anyway, I recently started to have a thing for her and now I'm falling head over heels. I don't know if I should tell her because I'd rather keep a close friendship with her than lose that and have things become weird between us if I tell her. What should I do? I feel like even though we're friends the chances of us being anything more is slight because of the age difference more than anything else. I just don't know what to do. Help me out here.