Is it normal cant stop thinking sbout someone i havent really met?

There's this girl obviously and I've known her since primary school and all through high school, when i say known like i know her name and basic shit haven't had the balls to talk to her, anyway, since i can remember I've always had a thing for he, don't know why but its always been there. Haven't really spoken to her because i never no what to say, i said i would speak to her once we left school but then whats the point? Long story short, I'm a bitch.

Anyway we left school and i kind of got over her, then we ended up being at the same Uni for about 6 months and then it all started happening again. When that had finished i didn't see her for about 3 months or so and i kind of forgot, well not really just not 24/7 bullshit thinking about her. Last week i saw her in the car and now i cant stop thinking about her again.

Don't get me wrong I'm not some kind of freak that's going to start stalking her or anything and if she ever was in some kind of trouble id be the first to step in for sure. All i really want to do is get to know her and see if she really is what i think she is, but i cant talk to her and now i cant stop thinking about her...is this normal?