Many of those symptoms are crossover symptoms with ASD and the two so often go hand in hand.
Working with young children with neuro diversity and developmental issues, the thing I find so fascinating is the uniqueness. No two ADHD and/or ASD cases present the same and when you factor in the sufferers IQ, which can make a huge difference to the presentation and prognosis, the number of variables are infinite.

Im almost 60, and if I look back to my school days, I can now understand the 2 or 3 kids in class who were sadly undiagnosed and didn't get the help they needed. The class clown, as you pointed out, but also they quiet kid who stared out of the window.

ADHD can be a serious learning difficulty which many would do well to remember, exasperated if you're not the brightest.

Anyway, I won't waffle on anymore.

Best wishes with your diagnosis and I hope it answered a few niggling questions you might have not been able to put your finger on for years!