Why isn't she being honest how she feels.

Hi guys.
Ill just get straight to the point. Im 19 years old and ive had a thing on and off with this girl for 3 and a half years now. A bit about her. She has had a bad run with boyfriends in the past. her last three boyfriends cheated on her and treated her like shit. Shes quite shy and doesnt like admitting to her feelings that often and is scared of relationships because of her past experience. She has come to terms of thinking that a relationship means she will b told what she can and cant do. After being together last year for quite a while we 'officially' went out. I have been with several girls but out of everyone this girl tops them all. She understands me, shes fun to be around and we both enjoy the same things. our relationship only lasted a month before we broke up and stopped talking because of fighting. Up until a week before things were going great. But fighting tore us apart over small things. and to be honest i think she was scared of getting hurt again so pulled out early instead of working it out.

We stoppd talking for 8months after that but now in the past 2months she is back on talking terms. Again we will see each other and go to the movies etc just like we did previously. Again the strange thing is she will show signs of liking me, she will smile wen shes with me for no reason other then me looking at her, she will hold my hand. she will kiss me back if i kiss her. She will cuddle up to me on the couch. But if i ask she will say she doesnt want a boyfriend and we are just friends. I have asked her if she does those things with any other guy 'friends' and she said definatly not. I dont know why she cant be honest and admit that she likes me. I also dont understand why she doesnt want to be in a relationship. When we are together we are never fighting. Fights will only start occasionally wen she gets jealous of me with another friend (girl) or if texts messages are misunderstood. Other then that, in person we have a ball.

I dont know what to do. I want to be with this girl. Shes one girl that makes me feel like no other one has. Is she just leading me on or is she just scared to get hurt again? She says things like i dont want a boyfriend right now, i like being single. But she never goes out with other guys, she never goes clubbing. Its like we are in a relationship but we arent.

Someone please tell me what to do.
Do i stick at it and help her feel secure enough around me to open up? or is she just leading me on.

from,
confused individual.