Getting an ADHD diagnosis(?) is quite ambiguous

A few years ago, I wondered if I might have it too...
So I looked into how the testing and medication process works,
and it seems they mostly use psychological testing..
There are reports that brain imaging shows differences in people with ADHD compared to typical brains, but apparently, that isn't definitive enough..
As for medication... some cases suggest taking it consistently,
while others suggest taking it only when you need to focus..
They say it's difficult to provide a definitive diagnosis based on physical evidence alone.
I looked into it again recently, but nothing regarding the diagnostic process seems to have changed.
So, I've decided not to take any medication..