A couple of things I agree with. I, too, have never heard anyone say that they were sorry they did not wait longer to medicate their child. If this is hard for you, imagine how hard it is for him. If you wait until things get to a real crisis, it can be extremely difficult, if not impossible, to recover from. Once you decide to treat, it is not an easy fix - finding a doctor that takes your insurance can take tens, if not hundreds, of phone calls, waiting for appointments can be months, finding the right medication is trial and error. And, if you don't treat, your child may self medicate, though I don't think you at risk of that at age six.
That aside, what you really have to do is to identify what it is that is driving you crazy and then change your environment to make your child successful. Pick the low hanging fruit so you see success - it will motivate and energize you. Here are some things that I remember doing. My son would leave everything lying around. So, we identified places where things could be left. For example, backpacks went by the back door, shoes on the stairs, coats over the railing in the entryway. Did I love this - no, I am a neat freak. But, it was something that worked and I could live with it.
I also started with bedtime routine and worked backwards to develop routines that were successful. At bedtime, kids could have a snack, then we all got together to read on my bed. Since my son didn't read until he was older, it was me reading to everyone at first. For mornings, I gave my son a list on a clipboard each day. At school, he had a similar set up - he got a list taped to his desk of everything that had to be done between the time he got to class and the time class started.
I had to work on me as well. It's pretty normal for kids to play hard and loud. And, mine was a climber, which made me nervous. I had to let it go when they were outside and set aside space inside for them to play (i have other kids). In the space I set aside, we didn't always clean it up everynight because they would make elaborate set ups with their toy cars and didn't want to have to start over each day.
Anyway, good luck.