I was having this sleeping problem also, was woke up middle of the night to alert myself to change back left position; ended I had terrible sleep. Just checked with my gynae, she said it's fine to sleep any position as long as you're comfortable & it won't harm the baby. Now I feel more relax while sleeping:)
Its better on the left for blood flow but hey gettin a good sleep is more impt ok.. u will nd it!
No prob sleeping on the right but its highly encouraged to sleep on yr left.. my take on it is, sleep whichever way/side that will give u a good rest..
Farhana Samsudin