My other T is also slim and pretty. And then she's also nice, funny, smart, social. (and only about three years older as me.) When I met her for the first time I thought ''****, she's pretty and young. That's not going to work''. I thought she would judge me because I'm fat and ugly. She hasn't (at least not that I know of).
She turned out to be a good T, the only good one I had so far.
In the last year this actually became a bigger issue for me. I envy her so much. Somewhere in the last weeks before she went on leave, it as one of the things I wrote about in a letter full of worries. But she didn't started about my envy for her, and I was afraid to start talking about it.

I'm not really sure what to do about. It's probably best to talk to your T about it. And to work together on your self-esteem.