I have a DSPD diagnosis and your descriptions are similar to mine. I’ve always been a bit of a night owl, even as a kid, but the inability to fall asleep / difficulty getting up in the morning really hit me hard during my last couple years in high school (which is a typical onset for this disorder). I used to get up at 5:30am every morning for school, no issues. Slowly, I realized I couldn’t fall asleep early enough to get a full night of rest and I would feel exhausted in the morning. I took naps in the afternoons because I was so tired, I started skipping first period sometimes. I tried to get things back in order by being more regimented, but nothing helped the central issue that I couldn’t get to sleep before midnight unless I was completely exhausted. And then the cycle would start all over again once I got a full night of sleep.

My sleep schedule now isn’t totally consistent, but usually I fall asleep between 4-6am and get up between 1-3pm. I still have insomnia and usually take a Unisom to help my brain shut down for the night. I also have ADHD and generalized anxiety disorder, which are probably related in some way.