I know you already got a ton of answers, but I hope you still get a chance to read mine. I agree that she sounds like she's in pain, you said that people with no psychological problems can't understand, well I hate to tell you but this girl has serious psychological problems. They not be the same ones you have, but they're still there.
You sound like a very sensitive and caring person, I know you care about this girl and want her to like you but you need to understand that you can't fix her or her situation. I am also very sensitive and caring and I tend to get mixed up with people who are needy of attention and love and they totally suck me dry. You might want to take this as a warning that this girl needs help, if you feel emotionally ready to help someone else, than try. But more than likely, you're suffering from SAD because you don't take care of yourself, so trying to take care of another would be very difficult and draining. It's time to take care of yourself, give yourself the love you wish she was giving you.
I know that sounds impossible, I've never quite been able to do it. But there are ways. Right now I'm working on doing inner child therapy. It was really hard to get started in it, but now that I am I think it's really helping. I can see myself when I was little as being so awesome and cool, and I can tell her that and that I love her by talking to her like she was an actual kid. It's hard to explain. I wrote about it in my blog if you'd like to read it, here's the link:
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