That is a tough one. I found that depending where bubs is 'sitting', depends on which way I sleep, plus the constant loo breaks keep me up.
I have found that sleeping 'propped' up with a few pillows is fairly comfortable or my leg over my other leg with a pillow underneath and a pillow behind me.
You might be overtired too or going to bed too early. I did that mistake and found I was waking at some ridiculous time in the morning only to have to get up in 2-3 hrs. See if you can go to bed a bit later and when you are really tired, that way you might sleep for a bit longer or have a deeper sleep??