Remember runningrunning, if people look at you they're probably wishing they were fit and healthy enough to do what you're doing.
As Namaste says, we often have a distorted image of ourselves. I've had real issues with various bits of my body over the years but I've gradually got better at seing myself as a whole, which is how other people see you.
I nearly lost one of my legs through illness as a child so when I start worrying about their size/shape I remind myself of how lucky I am just to have two legs which work ok. I'm far from perfect but I'm doing my best with what I've got !
Have you got a trusted friend/relative who could point out all the positive things about your body ? It might be quite a revelation !xx