There is no one cause of "can't get a good night's sleep" syndrome. There are many 'sleep-breathing problems" besides sleep apnea. A new visit to a sleep doc will determine if it's a physical problem. I suspect you have both that problem and a psychological problem that there are "pills" for but I would suggest self-hypnosis technique for getting and staying asleep which is far better than a drug.
I'm sorry. When I just re-read your post, it does seem like you have had a sleep study. May I ask, when was the last sleep study that you had, and what was the resulting diagnosis?
A sleep study should identify any physical problems, such sleep apnea, restless legs syndrome, etc. I would see a sleep medicine specialist and do that. You will go to a "lab" that looks like a motel room, and you will sleep with monitors hooked up to you. The doctor looks at the readouts in the morning. The first thing to do is to make an appointment with a sleep medicine specialist. Good luck.