Sleeping positions

Hi ladies! I’m 21 weeks pregnant and I am having so much trouble getting comfortable while sleeping. Before I got pregnant I always slept on my stomach. It was an adjustment not sleeping that way. I have issues with my hips from way before I got pregnant and so sleeping on my side has become more uncomfortable the bigger my little guy gets. It’s been almost unbearable for the past week. The only way I can sleep comfortably is on my back, which I know you’re not supposed to do. Although I have been propping myself up with 2 or 3 pillows, which I’ve heard makes it a little better. I just don’t want to do anything to hurt my baby. Any sleeping tips from people who have been through this?