Is she only being nice to me and doesn't want to be friends or anything? Being pretense?

I'm a insecure shy GIRL underclassman with major family issues and this upperclassman was very impressed with my music. She goes red around me sometimes. Like she started asking me to play and bring my guitar in and crap. She is very popular and when I did she wouldn't say anything. Took place in the cross country season. Track season she helped my sister with a lot of problems so I wrote a song for her and showed it to her. She admired it with great appreciation and walked in the same hallways and stuff. Then I hinted her with it by showing to her on fb. She stopped going my way for a while afterwards but still said hi to me and stuff. I mean I wholeheartedly admitted to her on fb I thought of her as a sister. She didn't message me back about other stuff than the song I wrote for her. Like I try to talk to her about other stuff nada. But she comments on my photos and stuff on fb. On the last day she hugged me and said keep in touch. I gave her my number but she never gave hers. Should I jut move on with life and forget her? I mean my family is zoo dysfunctional I felt loved by her only for once and it hurt. In freshman year cross country she never paid attention to me only this year when I displayed my musician skills. I went to her graduation didn't speak to me. But lately shes been poking me on facebook...