Dear E.,
You have started in the right place, the internet has a wealth of information to help you. You didn't say who diagnosed your son, but usually it's done by a psychiatrist or his M.D.. The way you describe your son, it wouldn't suprise me, but it's not the end of the world.
I am not a fan of medication unless it's really needed and the meds for ADHD children have lifetime side effects. If you have tried everything else (it will take a couple years to try everything else) and nothing is working, then medication is warranted. That is just my opinion from the standpoint of being a parent of an ADHD child, and ten years of working with ADHD adolecents.
What worked for my daughter was a combination of diet changes and behavior modification. It took a couple of years to get it fine tuned, but we did. My daughter is now 26, never had meds and has a normal life including graduating high school with a 4.0 GPA (that took some really hard work!).
The diet I used severely restricted gluten (wheat) and it made a huge difference in her behavior. She had sugars, but the timing of when she got them was everything. In ADHD kids things like sugar and caffine that are usually uppers for everyone else act as calming agents in them. To this day coffee will knock my daughter out! She got some of her sugars with breakfast and lunch, helped keep her calm at school, but none after school when she needed to run, play and get energy out. Things like fruit where usually a bedtime snack, helped her relax. I didn't have the internet back then (She was diagnosed severe when she was three!) so I went to the library and researched it all. The behavior modification started out as simple as 5 min on task, 15 min free time, and gradually shifted until she was ready for a school day (thank goodness for much needed recess).
I have heard wonderful things about the Feingold diet from parents of ADHD kids who are young right now.
I don't know what kind of insurance you have, but an ABA therapist may have some great input for you, and if that isn't an option, look on the internet for behavior modification information.
I wish you the best of luck, and know that you are far from alone out there. My hats off to you for not just throwing drugs at the problem without trying other things first :)