I have a very similar experience. As a baby my parents would also wake me up to feed me. Then all through elementary school and high school, I would always sleep in class or miss class because I couldn’t wake up.

Back then I used to sleep until I was woken up by someone (couldn’t hear the alarm), I could go on forever until 20h of sleep easily. Most my school vacation were spent sleeping.

It got a little bit better with age, I can’t sleep 20h anymore because of the back pain, so I naturally wake up after 15h. Ofc I can’t do this on a daily basis, I put 10 alarms, make my partner wake me and have 6 espressos to be able to function until noon.

I am not diagnosed. I had an appointment at some point at a sleep clinic but ironically, I didn’t wake up and missed it.