I still sleep on my back and often it is the only comfiest position I can get in. I do however occasionally put a pillow next to me on my side so that when I am on my side I can rest my tummy on the pillow, sometimes I even put the pillow in between my knees and leave a bit hanging up so its touching my belly and that is quite comfortable. I would just do what makes you the most comfortable and if you are fine sleeping on your back then I would do it. Your body will tell you if something is wrong