I wake up during REM sleep typically. Is this why I'm sleepy all day even on 9 or 10 hrs sleep?

Possibly. Rem sleep is an important part of your sleep cycle. If you were in my office, i would ask you how you know you are waking during rem sleep. Usually, people get about 2 hours of rem sleep per night, in 3-4 different episodes. If you are having numerous awakening through the night, even if it isn't during rem sleep, that would explain your fatigue. Seek care with your physician if it persists.
Sleep test. All of your symptoms may indicated sleep problems that can be life shortening or life threatening. The only way to know if there are serious problems is with an overnight sleep test. I encourage you to seek help.