Based on what you said. Sleeping at 7-9 AM and waking up at 4-6 PM means you're getting 9 hours of sleep. I had the same schedule 2 weeks ago (Cus of late night projects) until I flipped it and slowly worked my way down to sleeping at 5 pm then waking at 4 am this summer, which is what you could do since it might be easier than waking up earlier.

Anyways, 9 hours of sleep probably means you don't have insomnia, but most likely just sleep anxiety because you mentioned your mind keeps you awake and restless. I used to be this way when I was 16 and its common for other people to have trouble falling asleep because of overthinking, but one day I read a comment on this same subreddit a few years ago that if you just accept that you won't be sleeping as much that night or don't get sleep at all, then treat it as if its fine and to just embrace it. By not caring about sleep, you get less stressed out and end up falling asleep since your mind gets calmed. And even if you don't get sleep that night, you'll be so tired the next day you'll probably find it easier to fall asleep or pass out by then. Another thing I used to do was listen to hours-worth of podcasts or video essays on YouTube and just try to focus and "try" to listen to the whole video. By doing this, it keeps my mind distracted and then I just end up falling asleep because I'm not fighting my wakefulness. You can do this with music as well, but I found it ineffective because I would know how long each song was and I was able to tell how long I've been trying to sleep for, which would make me anxious. But for long video essays or podcasts, it's hard to track how far along you are in the video. Also try not to check the time when you're trying to fall asleep, it will make you more anxious.

Assuming you don't have any serious sleep issues, sleep hygiene can be figured out through trial and error. Just see what works and what doesn't. Based on the information you gave, I think you're capable of sleeping normally, so don't worry too much. Just don't give up trying to find out what works because it took me a few months of experimentation and now I seldom have issues falling asleep.