This can become an issue later in pregnancy. The concern is that sleeping on your right side or you back will cause a decrease in blood flow to the baby. With my son I always tried to start on my left but kept waking up on my back. My MW told me that if there was an issue, my body would let me know. I would feel dizzy and ill; it would be pretty clear that I needed to change positions. So, if you can sleep comfortably on your right side or your back, then no worries. If you start to feel like something is off when sleeping in those positions, switch to sleeping on your left. As with so many things, it is best to listen to your body!
Blessed Mama to the sweetest boy in the world (11/9/13), one angel baby, and two fur babies: Mattie Dog and Stanley Cat.
Re: sleep!!!!
Relax & get some sleep however you feel comfortable