I didn't have time to read through the entire thread so I apologize if some of this was mentioned before....
A sleep tech told me that it sometimes takes weeks or months to feel better. It can actually make you feel less rested at first due to what they call REM rebound. Sometimes patients who were severely sleep deprived go directly into REM sleep as soon as they fell asleep once they were titrated and stay in REM for most of night. Most know that REM is the stage of sleep where you dream, but most are under the impression (I was) that you get your best rest in REM, but in fact you body and brain are quite active in REM and you are not getting refreshing sleep. Stage 3 and 4 is where you get your most restful sleep.
You could also have other things affecting your sleep quality. When I did my second sleep study the Tech told me that they were able to cure my apnea with a fairly low pressure, but I had many disturbances due to my hyper sensitivity to sound (can't remember the correct terminology). She told me that any of the other patients would buzz the Sleep Techs station, or doors opening, etc. it would disturb my sleep, even if I didn't wake my brain waves would spike in reaction to the noise and reduce my sleep quality.