O...M.....G!!! You have the EXACT same story as I do!!! And my son is now 12!!!
He had issues since kindergarden (spent more time 'benched' at recess than playing the whole year) and was suspended in 1st grade, couldnt concentrate, wouldnt sit still, etc, etc, until I FINALLY stopped being in denial and blaming myself and got him evaluated.
I sat in the Dr's office telling Doc all his past and all his 'issues' and then I told Doc it was ALL MY FAULT since I didnt give him enough attention, not enough one on one time, didnt feed him healthy enough, got divorced when he was 2, etc, etc....it was all MY fault and he was really a good boy. What really hurts is he would tell me he felt like he needed help from a Dr or something and that he needed help to control himself. I thought those were just excuses so he could get away with bad behavior. But when NO punishment on earth works, ya gotta figure something is up....
You know what I found out? I was WRONG to ignore his pleas for help!!! He had/has SOOOO many signs and symptoms of ADHD that there was just nothing else to do but give him medication. I was in such denial for SO many years, I felt so much guilt. I wish I had gotten him help sooner, but theres nothing I can do about that now.
Now I try to watch his diet, get him excercising and make sure he takes his prescription. The nice thing about his med is I can let him take weekends and summers off it, as long as its what we both want to do and can handle.
One good thing is alot of kids outgrow it, and if not, as they mature, they are better able to handle their symptoms and behaviors.
Its still a rough road, but I know it will get better! I hope things go well for you and you get the answers and help you and your son need.
Oh, and DoNT count on the school for a diagnosis- that should come from a medical Dr with experience with kids with ADD/ADHD.