From reading all the responses you have gotten, perhaps you can see that it is perfectly "normal" for many people to feel the way you do.
I would say that you need to cultivate being happy being by yourself. Not because I think you always will be alone, but because you have to be able to be happy with you if you expect anyone else to be happy being with you. You have to like you. There is a difference between being lonely and being alone. You need to be able to be alone and not be unhappy about it. Develop your interests, deepen your faith. Don't look for other people to fill your void--you have to do that. And when you are happy with you, it will draw others to you.
Another thing... Are you waiting for friends to ask you to do something or are you ever the one to make the plans? I am way older than you, and to this day, mostly, it is me that arranges to see friends. It isn't that my friends don't like being around me or anything, but I think everyone falls into their own routines and into their own little world. I have them all over for dinner and we have a great time. "We should do this more often..." they say. But no one does. Should I sit and wait for them or wonder why they aren't the ones to do the asking? Nah. It might never happen then. ;) So if you want to have friends, be a friend.
As other people cautioned: beware of anything you read on Facebook. If their lives were so busy and full why do they have so much time to report all their "fun?" And really, some of what people say--is that really what you want to be doing anyway?
College doesn't last forever. College friends often don't either. People do walk in and out of our lives. Learn to enjoy them and treasure them while you can. Some are only meant to be there for a while. The best you can take away from college is the Knowledge you will have gained. May God bless you and guide you.