I am far, far, far from skinny! And I had the same hang ups, but my first wg, was a sexy as hell 20 something. All these things went through my head "would she find me unattractive? Would she think my personality sucks etc, but it didn't matter one bit. When I got there I was treated as any other punter.
I now see it the same way I see my own job. I'm a mechanic and work on old shitters and top end sports cars, but at the end of the day it doesn't bother me as the colour of the customers money is all the same. Its just a job.