What should I do now? Please help?

I have been dating this girl I love so much for the past 3 years on and off, she always broke up with me. We are almost 16 and I feel like I’m loosing her.

Anyways, Lately I have been wanting some space from her, like I haven’t been talking to her as much through texting etc, but in person we are best friends still. She always has talked to other guys, like as “friends”But when I look at it I see flirting, smiling, hitting each-other, laughing, you know.. I told her to stop a couple times and told her how it felt and what not and she says ok and w/e and does it a couple weeks later. The one time I had “a friend” when we were just joking around she flipped sh*t on me.Things are always one wayed for her, If she does it ok, if I do it its the end of the world.

We have been fighting a lot lately and I don’t know about what, Sometimes its over simple things like “why I’m upset” or “Do you want to hang out today”. And no-matter what I say it ends up in a fight. We both have family issues and whatnot, she’s always mad lately.

She told me a month ago that she might be pregnant and I don’t know how because she is on BC, she missed some days, took 2 the next or w/e but we made sure not to during those days.

I feel like im loosing her, Im a nice guy but I don’t know what more I can do, all I want is a little space here and there cause I like my own time without being smothered, She always liked attention and being the best at everything.

I’ve been having bad grades in school and people are mad at me and I don’t know what to do anymore, If she leaves me ill be struck, ill probably drop out of school, give up, stop trying at anything, then my mom would send me away to a group home.

This may sound dumb and pathetic but im looking for a little advice on what to do, I feel like I have nothing worth trying for anymore, I cant handle a baby at this age right now. Abortion is not an option and never will be, Please help.