You don't have to be chronically late to be diagnosed with ADHD. I am never later for anything, but that's due to some good coping mechanisms I learned over the years (that basically amount to "do nothing before the event and leave an hour early")

It's possible to have ADHD and good coping mechanisms that mean you don't meet every single hyperspecific criteria on a list like this. Hell, you might even cope so well that you didn't get bad grades in school. The diagnostic criteria looks for focus deficiency, executive dysfunction, impulsivity, restlessness, poor working memory. There are standardized tests for this.