You seem like a sweet guy, and your story is inspiring as well as endearing.
I care about what it's like to spend time with a guy, not how closely he resembles an Abercrombie model. I don't expect my clients to be "hot" nor do particularly I care if they are... I DO, however, care whether or not they are nice, interesting, intelligent, considerate, etc. If that criteria is satisfied, and I have a good time with you... there is a high likelihood that I will find you attractive in spite of any physical issues.
If it's something that could interfere with performance, I might want to know beforehand... but, I've been surprised by everything from ED to morbid obesity to Parkinson's to a proclivity for hard-core BDSM... none of which I was prepared for. Part of my job is to deal with all of those things I'd never be able to prepare for, even if I tried to.
But, if you feel that you need to mention it, in order to feel better - and to get it out of the way, so that you can forget about your apprehensions during session - then by all means, let her know.
If she does turn you down, you were likely better off not seeing her, anyway.