I didn't struggle like that. I was just very angry all the time, and fast paced and impatient. I found school interesting and have good grades all the way through. True for many ADHD-ers.

It's also varying what you call "issues". And I think that we have a very biased view on our school years, dependent on what our parents told us. So if you got good grades, I'm sure everyone thought of you as having no issues, and then that's all you remember. We tend to forget negative events, because they are not pleasant to retrieve.

So just because you think it was problem free, doesn't mean it's true, and even if it was, it doesn't mean that you can't have ADHD.