How can I make girls like me and have better self esteem?

Hi, I'm Menachem, to start things off, I'm 19, single, and I'm a college student in New Jersey. My question has to do with girls and how to deal with the issue of loneliness in general. Although I've liked alot of girls over the years, the only real girlfriend that I've had was in high school, but I broke it off because i decided we weren't right for each other and she had alot of very serious issues that I won't get into right now. The point is that I'm a very lonely and insecure person, and I don't know what to do about it. I'm extremely self-deprecating, which is something that my former girlfriend complained about when she said that I was too vulnerable. I know this is a problem. I'm oversensitive and even when I'm around people who are supposed to be my friends, I feel like there's no connection, and no one understands how I really feel inside. I know none of this sounds very good and I can understand why insecurity is a turn off for girls. I can't help feeling like something important is missing from my life, and I think about meeting a girl that would love and understand me and make me feel better about life so much that it frustrates me when it never happens. I'm actually not that bad at talking to girls but no one that special has ever come along, so I just feel empty and dissatisfied. I don't know what anyone here can do to help me, but maybe someone has advice about how to help me deal with this stuff