I used to have energy..

Chelsie • Married: 04-12-2015. Due date: 06/28/16. Currently pursuing a Master`s degree in Secondary Education (6-12 grade).
But now I'm always tired!! My sleep patterns are the same but for the last week I'm constantly tired! I'm 37+3 weeks with my first baby.
I'm off for the summer because I'm a teacher and I get up with my husband to fix him lunch for work. As soon as he leaves I go back to bed and sleep another 2+hours.  Is it normal to be this tired all the time! Where did my energy go?