Some advice or encouragement?

I don't have many friends but I know a lot of people & im single and have been for a while. I'm so lonely that it's getting depressing not only is it depressing but it's lowering my self esteem. I'm not an introvert. I work full time & I'm in college full time. I try everything to meet new people but I just can't. I don't know how much longer I can take this depressing boring life of mine. I'm surrounded by people 10-16 hours a day between work and school but still am so lonely...