Stressed about sleeping on my back

I am a natural back sleeper. It’s the most comfortable position in the world to me. I’m 17w now and trying to train myself to sleep on my side. It’s been very stressful and uncomfortable. This morning I woke up and my leg was completely pins and needles from trying to sleep on my side. I’m even trying to put a pillow between my legs to help to no avail. How necessary is it to become a side sleeper really?? I plan on asking my OB at my next visit, but it’s still a few weeks away. Thank you in advance!