Why do I feel like this?

Well, I am an 18 year old in College and I have always felt like I didn't belong to anything. I don't feel good I feel lonely, I kind of want to say i'm depressed but I have not actually been tested for this but it's how I feel. People don't think I have any reason to be depressed because everything on the outside looks good but it's just that i'm not happy I do not have friends, I feel sort of like an outcast. I have low self esteem and I am not confident at all. I have this one guy who I've been talking to for about 3 years now and we sort of date but I still don't feel he really likes me or "loves" me as he says but I don't feel like anyone does I sort of feel like people just put up with me. I'm just not happy and I'm not sure if it is depression or whatever but I don't feel my mom would understand she doesn't believe in things like that and I put on a hard exterior in front of family like nothing bothers me but deep down I just want to cry everyday. I guess college is a time where they say people find themselves so I guess I shouldn't stress it too much but I just don't know how to handle this, I do read the bible and pray about this. Thanks