9 year old boy, trouble sleeping

My 9-year-old son has always struggled to some degree with sleep (We were told when he was born to wake him every 2 hours to feed him, which was a terrible idea and utterly destroyed his sleep pattern; I don't think he's ever recovered fully from it). But the last year it has become worse. He won't go to sleep at bed time (which is not new, just more pronounced), often laying awake in bed until after 8 or 9 at night, but then he doesn't want to get up in the morning. (We get up at 6am.) From observation, I know he does best with a solid 12 hours of sleep. Otherwise, he becomes very fragile mentally and unfocused physically. (Crying when feeling provoked, easy to provoke, etc. Not paying attention to what his body is doing.)
We've tried letting him stay up until 8, but then he stays awake until 10. He won't close his eyes, he gets up multiple times to pee, he gets frustrated and angry.
If he slept well, I doubt he would need 12 hours of solid sleep, but he tends to sleepwalk (before midnight), cries out in his sleep (all night), rolls around, gets very angry, and (especially when he has loose teeth) grinds horribly (after midnight).
We tried phytolacca decandra 12c 3 tablets each night based on a study I found that seemed to fit his symptoms exactly. At the time, I couldn't find melissa officinalis 12c, so I used melissa officinalis tea instead because the study indicated that although the grinding decreased the boy's night terrors increased before the melissa was added. In combination with phytolacca, I used Cina 30c 3 tablets before bed, based on a note I found in a similar situation where both remedies were used. In both cases, the grinding and sleep problems were resolved within two months.
For the first week, his sleep seemed much deeper and more restful and his grinding decreased. But it didn't last long, and now we are back where we started, possibly worse.
I tried taking a break from the remedies and starting back up, but with no success. I've used the Remedy Finder, but none of the remedies it gives me seems to fit him very well, and I don't want to just keep throwing remedies at him.
Overall, he's a very pleasant child, energetic and happy. He is used to having attention and his way, very demanding. Doesn't like to be alone. Invents reasons to be anxious. Worries about holidays months in advance. He feels the urge to urinate frequently and worries about urinating, especially when going places. He tends to have "anxious" stools when we are going somewhere or planning something, even if he is happy about it and cheerful. He is an only child, so to be fair, he is used to being spoiled; but he hasn't been "spoiled" by it. For the most part, he is usually quite thoughtful and aware of others.
He eats very little sugar, in fact doesn't enjoy sweets much at all, and, his diet is excellent. Lots of fruits and vegetables, unprocessed foods, and no chemicals. He isn't on any types of medications. Has a very stable home life, and no obvious reasons to be anxious or upset.
Thank you so much for your insight.