Please don't take this as anything more than a stupid question from a non-medically-trained stranger (who would like to help): Have you ever been formally assessed for generalized anxiety disorder (GAD)? Lot's of us simply cannot turn our brains off. I'm one such person. I fall asleep too quickly, according to my Samsung Galaxy watch and its managing health app on my phone. I get a nod of approval if I can stay awake for at least five minute after putting my head on my pillow, but I often get the orange or red square with the exclamation mark displayed prominently inside it. Now, I know some would kill for that problem 😀 but falling asleep is not my particular predilection. Instead, it is awakening near 0500 (I'm a night owl and am rarely in bed before 0030 hours, usually more like 0115). Once I have had some sleep, it's hard to get back to sleep.

I feel for you. You have apparently responsibly and actively pursued most/all readily available and do-it-yourself remedies or tricks. I do know that our bodies work actively to neutralize the initial potency of any medications over time, whether heart arrhythmia medications or sleep aids and mood-altering drugs. Sometimes all that works, for a while, is the optimism we have when we are suggested or offered something novel that we haven't tried.

I hope you get both carefully considered and useful suggestions here, and that you eventually find relief.