Gosh, after reading all of your posts, I feel lucky to have a very apparent condition (right hip disarticulation at age 23) I've been this way for 50 yrs. I've had a successful career and a very successful farm business, My wife and I have launched four successful kids into the world.
I couldn't bear to have a handicap sticker, placard, or plate unless I really needed it, which I don't yet. Sure, I hurt in several places (shoulders, ankle, wrists) but I've crutched to the summit of Ibapah peak and a lot of other places that are hard to get to. I get asked fairly often why I don't use the handicap parking. Other people need them more than I do. I encounter people every day who are way worse off than me, whether their condition is apparent or otherwise.
By the way, I prefer the term crippled over the term disabled. I am totally able so far.