second trimester

Amanda
Question for other moms out there. 
I am a FTM, and currently 17+6 So I'm well into my second trimester. My first trimester was a breeze; no morning sickness, no tiredness, basically no symptoms. However, the last two weeks, I have been so exhausted. The doctor and everyone tells me energy levels should be at their peaks, but I could literally sleep 12 hours and it not be enough. Any other moms feel this way? Is it common/frequent. I usually get between 11/12 hours of sleep a night, work (I am a teacher) and want to come home and sleep again.