This could be classic UARS, especially since you say you’ve had sleep issues for as long as you can remember. Half of UARS patients don’t benefit from CPAP. They require orthognathic surgery to resolve their UARS.

Usually sleep-disordered breathing gets worse with time/age, if left untreated.

You should join the UARS Facebook group and ask some questions. They’re a helpful bunch.

Also, you might consider doing a paid consult with Dr. Steven Park. Google his name + UARS.