Should i stay or should i just move on...

I’m 17 and my girlfriend is 15. I’ve been with her for almost 6 months but it doesn’t even feel like it. I can’t see her that much b/c one, her mom doesn’t like me too much and yet I haven’t even met her, 2 she plays sports and has practice Monday to Friday. I never go to her house and when ever she’s at mine on the weekend, she lies to her parents when they call and say she’s somewhere else. When I drop her off it is so shady, I have to pull up and leave slow. I feel like I have to be like James Bond with this whole relationship. I was never the kind of kid to have a gf and everyone new that. I gave it all up for her and I really do like her a lot. I am not in love with her, but I do care a lot. I only get to see this girl once or twice on the weekend. The worst part is she basically lives down the street so it makes me crazy. The past couple weeks have been so shitty. All we do is fight and it’s just over stupid stuff. I always say, if only I could see you more things wouldn’t be like this. Deep down I know nothing can change and I will not see her anymore then I do now. Or at least until summer time, if we make it that long. This is the first time a girl has ever gotten into my head and it’s driving me crazy. She’s a great girl and not like the rest of them. I’m afraid if I let her go I will deeply regret it. I just don’t know if it’s worth it to go on. I’m optimistic about things getting better, but if they don’t, i’m fucked. I feel like I’m in a fake relationship, which blows. What do you guys think???