Hi S., I am actually a child therapist and helped start up an ADHD clinic in Jefferson County. I just had to throw in my two cents. It sounds as if you are very committed to working on the behavioral issues with your son and are doing so much research instead of denying the condition. So you are off to a great start.
I have to just say that often people feel like medicating is "giving in" or "giving up". It makes me sad when people feel like they've in some way failed by starting a medication. I don't see it that way at all. ADHD is the most researched and studied psychological condition. Study after study has shown that optimum results come with doing behavioral work (which you described to a 't') AND medication. Medication alone won't work, and often, behavioral things alone won't give you the best results. I've seen so many kids struggle with school and socially and it could have been avoided.
At the very least, I would say be wary of supplements. People have concerns about the medications, but at least they are regulated- supplements often have more adverse side effects and are not studied or regulated.
I am actually one that tries to avoid meds for my daughter as well. She has mild asthma and I resisted starting her on a daily pill for it. But she continually got bronchitis so it was more a matter of the lesser of two evils. You don't have to assume your son would be on meds forever. So I do agree with natural methods when appropriate.
I applaud the hard work you have already done for him, keep it up. And if you do decide against meds, I would recommend checking out several different books on ADHD. Get a mix of books- ones that promote alternatives to meds and ones that don't, see what fits for you.
But please don't get scared by claims of dietary problems and herbs. From your post, you sounded pretty level headed about that anyway.
Best of luck.