self-esteem!

I understand where you're coming from. I think that you should just try to listen to what these girls are telling you about yourself. I am certain that they see many good qualities in you or they would not be telling you that you are very nice! ^_^ I have suffered from low self-esteem in many areas for my whole life, so I can sympathize. But there is something good in everyone, and you should listen to the people around you and remind yourself that you are a good human being! ^_^

I'd suggest when it comes to girls, try to cultivate just being friends with as many as you can. Many girls really appreciate knowing a guy who is not always "hitting" on them and would be happy to just being "friends". How does this help you? Well, having several girls as "friends" is going to teach you a very great deal about how to get along with women. It will also raise your self esteem as you learn to get along with your female "friends". Then, before you know it, one of your friends will want to be even more. This has worked for quite a few guys. It can work for you.