My husband works nights too. Honestly I love it. I love having the bed to my self. It gives me more room to get comfortable. I always sleep with a body pillow and it helps so much.
I'm 18 weeks also. My boyfriend works nights too. The base advice I can give is grab a pillow or pillows to hug onto at night. I sometime go on YouTube And listen to rain falling or rain and thunderstorm sounds to help me get to sleep. U don't have to listen go those tho, for they have soft relaxing music and even waves or nature sounds. Try it out.