I can't stop thinking of a girl.?

[Steve]

I met a girl in September, it was about 2 weeks after the beginning of 9th grade. I just saw her talking to some guy and I kept looking at her, I've never felt this way until then. The next day I talked to her and asked her what her name was. I found out she likes to draw, a lot and shes good at it to. She said the characters she draws are mentally cracked (mentally retarded I guess). I didn't have much experience with talking to girls. I sat next to her in class everyday and I was always thinking about what to say next. Sometimes I would sit there the entire class wanting to say something and when I did it was something stupid. I thought maybe she didn't like me. I thought I saw her at lunch once and, turns out it wasn't her. I saw some goth kids and well, I thought one of them was her so I suddenly thought we can never be friends. I asked her where she usually was during lunch and she said outside of class. I was really nervous but I went there the day after. She was there and asked if I wanted to walk around and we did. I didn't know what to say but she talked more so I think it was okay. Suddenly I had a reason to go to school, I really was only happy when I was with her. She was only with me at lunch because her parents made her go to this school, her friends were at a different one. I was with her at lunch everyday for almost 3 weeks. I messaged her almost everyday on Facebook and when she didn't reply I felt terrible, I know its stupid. Than one day all of sudden she was absent, I thought it was because she must have been sick or something. The next day I went to where I usually found her at lunch and I saw her walking to class but with no backpack or anything. I said "You weren't here yesterday?". She said she wastransferringg schools, and I guess i just looked disappointed or something. Anyway I'm getting to the point, the next few weeks I messaged her on facebook, a lot even when didn't reply. I see pictures of her with her friends and I feel so stupid, why would she want to be my friend if she has her own. I'm not very social, I don't make many friends. She has very close friends and friends she can trust. When will I let go of this. She gave me her number on facebook, when i asked for it. She still gave me a chance even after me being such a creep. She told me to text her, so I did. I'm afraid to ask her if I could call her because I don't want to get in her way of being with her friends or something. I sound desperate don't I