Yeah, I grew up with a close relative that was diagnosed with ADHD, and I assumed I didn't have it since I lacked the "hyperactive" part that I saw all the time with them.
Turns out the 'H' isn't always referring to physical hyperactivity...
Does your mind wander when you read?
Do you lose things frequently?
Are you losing track of time frequently?
Do you often interrupt people in conversations?
Do you have 12 projects started but nothing finished?
Does your work area look like a bomb when off?
Keep in mind it manifests differently for everyone. I have it pretty mildly, so it's fairly well managed through guanfacine, a similarly mild medication, and lifestyle changes. The only reason my psychiatrist and I know I have it is it "flares up" pretty badly when I'm stressed and my life easily goes off the rails as I increasingly begin to exhibit more ADHD behavior.
It's also possible you don't have it as neurotypical folk experience most ADHD symptoms from time to time, just with less frequency and severity.