Could I be completely undesirable and worthless?
Really? What makes you believe that about yourself?
Well, I'm fat and clumsy and I am poor and I don't have a job
It is fine to think that about your at times. But when it becomes more frequent, you should seek some help and try and improve your situation.
I can't. So what if I'm fat.
You just said that you care, which means that you should strive to make yourself better. Most of your problems seem to be things that you can change, and you should try, if only just for your own self-confidence.