Momma
The test you’re talking about tests for attention span – you’re right. But that doesn’t prove if ADHD is a disorder or not. Can you tell me how many activities in regular life require you to sit for 15 minutes waiting for a certain letter to flash while doing nothing else. I believe most people would either fall asleep while doing that or get edgy.
I’m not entirely opposed to use of medication. In modern times a child needs to go through the school system. In my opinion they need to do that happily. I would try other educational methods (I’m not suggesting supplements necessarily) first. You need to have resources available to make it happen.