It could also be that deep down, your father does understand your problems, but is upset that he can't "fix" them. One of the hardest things for a parent is to see your child burdened with something you are powerless to resolve for them.
I've learned that over the past year myself, just from something as simple as watching my twin little girls when they've got a fever or an ear infection driving them nuts, and the medicine hasn't kicked in yet.
His own frustration at being unable to help you or "make you better" gets turned back around into riding you so hard. It's difficult for most any man to admit utter powerlessnes over anything, especially over something as important as the well being of their own children. It's a survival instinct, even when the odds are overwhelming, most animals, even people will keep trying whatever it is, rather than give up, on the chance they might just get lucky and overcome. When you add that basic fact to the likelyhood that your father is of an older generation, and is a military veteran, that's just a triple-whammy on his inability to cope with your condition by "giving up" and coming to terms with it.
Essentialy, I'm betting his entire attitude is really his own frustration and anger at himself for not being able to make you better.
If he's riding you really hard about being organized, working, your life, or whatever it is, and he's getting really unreasonable, you could try turning around, looking him in the eye, and calmly telling him: "Dad, the way I am just happened, it's nobody's fault, especially yours. I know you've allways done your absolute best for me. "
Be careful though. If your Dad is anything like the kind of man I think he is, seeing him cry even once will probably be about ten times worse than listening to him yell at you for the rest of his life.