I'm 23, and I'm feeling exactly the same way. Everyone has graduated college, and has real jobs. It's embarrassing looking for "college type" jobs while everyone I know is happy, beautiful, and successful when I feel so sad, fat, and failing.
I had similar thoughts today as I sat outside trying to get fresh air. "Why do THEY get to be happy?" I have never been happy in a stable way.
I think a lot of the problem stems from me not knowing how to talk about this with my real close friends, or my parents. So it bottles up inside me. But I know if they were to come to me with their problems, I would certainly let them know how important they are to me. And I think you need to consider that you are important to someone. Imagine a friend, or your boyfriend coming to you with these issues. What you feel for them, and how much you need them around is exactly the way the feel about you.