I sleep on both sides. I'm most comfortable on my right side. But i have experienced that tingling sensation as well. I honestly think it's the extra weight. I'm 5'1 and 114 pounds before the pregnancy; 132 pounds today so for me the weight is a bit much. I know that sleeping on your back is not good because of the lack of blood flow. Yet, it's my most comfortable position. :/
It can Happen to average weight women as well but it's more common in above average. It is just a pinched nerve basically. Your doctor should have gone into more detail with you. Don't be afraid to ask lots of questions! Be Your Own advocate!
Also sleeping on your left side is really not as big of a deal as everyone makes it or to be. You can sleep on your right side just fine. If I sleep in my left side sometimes it makes my heart race? But I often sleep on my back, a big taboo "NONO"! I'm 38 weeks bit is most comfortable sometimes.
I also sleep in a sitting position. All propped up against the wall. Sometimes on the couch.
You and baby will be fine, do what is most comfortable for you! Your body needs sleep! Trust in your body and yourself! And ask more questions to your doctor! Don't let him leave until you are satisfied!
I had this during my last pregnancy and my midwifes told me it was the baby sitting on a nerve, has never happened again since giving birth x