I've always kind of been a mess in relationships, 2 two year long relationships back to back. It's been about a year since I was in the last one. I had since then been diagnosed with bipolar.. My bipolar (unknown to me at the time) was the main cause of the failure of both relationships. I have always been a relationship person, and like you a people pleaser. Its been a long journey of self discovery this past 6 months and I know its no where near over. I have met a really nice guy who understands my situation and couldn't be more supportive. He would adore me, and yet I am still hesitant to get into a relationship or even consider dating him. I almost feel like I haven't learned enough about myself still to have a healthy relationship. I don't want to get in a new relationship and completely get in over my head again. I dont want to make the same mistake. You can't be in a healthy relationship if you aren't healthy yourself (doesn't mean perfect, stable may be a better word). Since my last boyfriend, I've had a string of sexual "relationships" that never got off the ground. I would become very attatched to them (would want to be very serious about them but my heart wasn't in it. I KNEW THEY WERENT RIGHT FOR ME). I would convince myself that I didn't want anything and that I was happy just being friends with benefits. I guess it was my way of coping with the loss of my last relationship. I was head over heels in love but due to my bipolar and a brain tumor, I put him through hell unintentionally. My love was pure but not healthy. I became very guarded, even though my heart was longing for something serious. I put space in between the guys and myself simply because I didn't want to get hurt, and I didn't want to mess ANOTHER relationship up.

You have to guard your heart, especially if you tend to put others before yourself but at the same time be open to new people and new experiences. Its all about the balance.
Always listen to a gut feeling, and if you find yourself nervous about where she stands. I'd try to be a friend since she is just out of a relationship. Approach with caution. DONT SETTLE for being a rebound.
Also, you said "shes not even right for me i just cant help liking her", find out if you really like her, or you just want what you can't have or like the idea of a relationship with her. It may just be appealing. If it could be potentially unhealthy it wont be worth it in the long run. Something better and more stable will come along.
Another note, you can't let old relationships affect new ones. You have to use old relationships as a learning tool. No person is the same, so no relationship will be the same. You can't change the past, only learn from it and move on to better things.

I typed this up in between classes, so if something doesn't make sense I'll clarify.