FYI, your sleep hygiene sounds good, but doctors have started to agree that primary, idiopathic insomnia doesn’t exist. It’s either anxiety or evidence of some severe disease or physiological condition.

So as long as you’re trying things, CBT is the most evidence-based long-term solution for the (very likely) cause of your insomnia.

Not to suggest diagnosis on the internet to people I haven't met, but for me chronic insomnia was actually narcolepsy. Ironic given that it's disease known for excess sleep, but the actual core issue is broken sleep structure. I had actually been supplementing with creatine for the past 6 months or so and recently gave it up. If it was having any effect it was marginal at best. The only thing that works is pharmaceuticals.