Welcome to NeuroTalk SloMo!
Mark made great suggestions. Since you've tried many ADD meds and they haven't worked very well, maybe looking at these different ways to adapt will help.
I have some similar problems from having MS. I take a medicine that keeps me awake (also used for ADD) and it doesn't really make me do better, but just improves my wakefulness. I don't know if that relates to how you feel from them or not.
I like Mark's description of being a 40 mph brain working in a 60 mph world. With me it's more like a 25 mph brain, but still the same situation.
Let us know what your doctor suggests if you talk to him about what else you can try.