Trust me, it's not that you are being judged at all, it's just unusually...Now doctors are going just by the nature of the business they are in - deal with more disabled people of all aged - but unless something sticks out that makes it obvious are are disabled, it's out of the ordinary.
Keep going to the same guy, the question generally only comes up once, and the attitude quickly goes away believe me....
I went through all that, occasionally still do (if so, when I need yet another type of doctor) - and I have been on Medicare since I was 18, and while there are plenty of physical issues with me, they are not all that noticeable until you really start paying attention to things, and observing.