Positions to sleep when 6 months pregnant?

Bárbara • I'm 28, and I have a beautiful baby girl born on May 30th, 2017 ^^ I also have a dog named Oliver and I love him lots!

I usually go to sleep to my right side and I wake up in my back, I've told my Dr. and she told me that doesn't mind and it's worse to be sleeping on your right side so now I sleep on the left side.

Which side is better? How much time are you supposed to lay on your back that is safe? I'm a little confused and I can't seem to find a comfortable position to sleep lately!