Here is an article on the effects of not reaching REM sleep, which is when you dream. If you don't dream, then you probably don't reach REM.

Effects of Not Reaching REM Sleep

Have you been tested for things like sleep apnea? I've also read that the more sun you get during the day, the more likely it is you'll get more REM/get into REM faster. If I were you, I'd just do some research and try everything you can! I wish you all the luck in the world in finding your solution