It honestly gets harder the last 10 weeks. Im 34 weeks and I always wake up on my back. My hips are starting to spread, so they are always in pain. As long as you start off sleeping on your sides you should be fine. My doc isn't too worried about it..
(:
I'm in the same boat. I am a back sleeper, always have been. I just can't get comfortable on my side. I'm 26 weeks, 27 on the 18th. I read after like 22 weeks or something like that its not good sleeping on your back cause it blocks important blood vessels to the baby. I forgot where I read it though. But I just can't get out the habit smh. Crazy! Lol
I'm 20+4 weeks now, and I used to only sleep on my right/stomach and now that I'm getting big it just that its only comfortable after awhile but once I became pregnant I mad myself get used to sleeping on my left
It is advised to sleep on your left side as habitual as possible in 3rd trimester. This is when the size of baby and uterus is big enough to cause trouble. Your left side allows blood to flow more easy to the baby. In labor if there is a heart decelaration the nurses are trained to get you onto your left side and on oxygen. This happened with my first. Scared me enough to always sleep on my side.
Arg I know the feeling. I'm an avid back sleeper and will roll onto my back in my sleep! No matter how hard I try!
From what I read it's better to sleep on your side as often as possible but if you end up on your back your body will tell you by back pain, or just plain out discomfort, to roll onto your side when you need to. Simply your body will know when it's time. :)