I was/am one of those parents who makes excuses for DS when I think he is on the inattentive ADHD spectrum.
I am happy and sad to read your post. Happy of course knowing that you will be getting additional support for your little guy. Sad that you feel spread so thin trying to navigate this reality. It is a good thing that you and DH have acknowledged what you can do to help your son, in terms of modifying your behavior. So many times parents expect a child to change/adapt while not taking responsibility for their own actions.
I also wondered, middle school, yes what a nightmare. Do you like the school that he will attend ? I know that you will have considered this, just curious about middle school options and which ones may be more suited to his personality (perhaps smaller class sizes, smaller school etc.).
Best to you K .... know it's hard