ADHD comes with something called hyperfocus, which is the ability to really focus on something you think is interesting. It’s part of why I got my diagnosis in my 30ies, because I never had an issue working full time in jobs I enjoy. There are other reasons, but that one was a big one.
ADHD has an interesting image to many of us as something that has you running around unable to focus, but for a lot of us, it’s nothing like that. It’s much more about energy deficiency. I’ll use myself as an example, I never had an issue working a lot, I did 50+ hour weeks when I needed to, only for a period and with rest afterwards (but that’s sort of how Danish society works, if you work 50 hours one week then you can take two full days off the next, or later). My “strategy” and I put that in quotes because I didn’t know it was a strategy at the time, was to go to bed early in stressful periods. This broke when I had my first child, since you can just go directly to bed when you come home from work for obvious reasons. As well as changing motivations and so on. But really, you won’t have an issue with focus when you’re interested. What you will have an issue with is things you aren’t interested in, and while a lot of us can endure them, we spend more energy than other people while we do it.
A lot of us even have a lot of the H but are still capable of sitting in a seat for an entire day. Sitting, not sitting still mind you. I sit wrong, I’ve astonished basically every “ergonomic consultant” or whatever their job is that comes around Danish offices every now and then by how I’m not broken physically from how I sit when they watch. Well until one of them was so curious that she decided to spend more than the usual 5-10 minutes observing me and realised I don’t sit in the same position for long. I’m apparently the embodiment of “the next position is the best position”, which is fun and all, but you probably wouldn’t notice if you didn’t look, so my H wasn’t obvious in my childhood years. Because I can in fact sit through an entire day of school and not listen to 80% of what is said. Same is true for meetings that should’ve been an email. The only real difference is that I’m twice as tired as a normal person who was also bored through the same meeting.
So in a sense, what you’re describing is text book ADHD, and may not be an issue for you. At least until some external influences change your situation.