Your problem is first of all that your G.P. presribed it. G.P's know very little about specialized medications. I took a drug that cause nausea. My doctor prescribed an acid blocker at the same time, so my nausea was minimal. In addition, it took me four month to get up to the therapeutic dose. I suspect that Stattera is a good drug, but you would need to take it more slowly. Why are you going to a neurologist instead of a psychiatrist? They are much more familiar with ADD.
I sympathize with your difficulties with medications, psychtropic medications have a lot of side effects and finding the exact right one is difficult. It can be, however, the difference between being able to function so it is worth going through different medications to find the right one.