If general doctors can't help you, maybe a therapist will David?
A lot of us here have some kind of general anxiety, and a few of us have a specific anxiety about our health etc.
As far as being fat and eating bad goes I think you have the power to change that. Even a light exercise program, combined with a sensible diet, could help you lose some weight.
I can make a salad in 5 minutes. It takes me way longer than that to order in junk food, or go out and get it.
But..if you have an anxiety about that as well, and I guess some people do, I think there's all the more reason for you to find someone who understands your mental health as much as your physical.
Finally the 4th step stuff. You've been stuck on that for a while. Have you talked to anyone at AA about it or about whats stopping you moving forward with it?
D