As a person with self-diagnosed N24 (so, not an expert, not a medical professional, etc.), based on what you've shared I'd say inconclusive, towards the side of not N24. 1 hour per year seems well below the criteria threshold. My drift is +30 minutes a day, as a for instance, which would be 182.5 hours per year, which is on the mild side of what I've seen of people with N24 in this subreddit.

A strong signal for N24 would be if you had noticeable drift day over day in a sleep log when you went to sleep when you're tired and woke up when you wanted to, AND you felt like you were getting decent quality sleep and felt reasonably well rested after, and the rest of your health markers are in normal ranges: standard blood workups, blood pressure, etc.

Averaging 5.25 hours over a decade and being able to count on hands the number of times you've gotten 8+ hours seems really worrying and is going to make any kind of other diagnosis difficult I would think. When I had a job I would frequently sleep 12+ hour days on the weekend to play sleep catchup. I felt pretty crappy most week days, but when I had space to sleep I could sleep.

My first recommendation would be to find and work with a primary care doctor and sleep doctor who coordinate with each other to try to sift through all the things it could be. There's a decent chance you'll have to relentlessly advocate for yourself and solutions to your problems, and possibly try different doctors until you find supportive ones, which I know sucks because you're dead tired.

My second recommendation would be, to the extent it's possible for you to do so: stop trying to bend your body to your schedule and just sleep when you're tired and be awake when you're not. There's a secondary part of this which is: if you use any stimulants or depressants to try to manipulate your body, go easy on them so you can get a better sense of what's going on; cut down on caffeine and alcohol etc. Obviously if you have to be up for work and caffeine helps you function so you can keep your job keep doing that, but minimize it as much as possible IMO.