Oh, I hear you!
But, I have found that from about 2 months my bubs could sleep with their heads in the crook of my arm. Sort of using my arm as a pillow. That way, I didn't have to raise my arm into an unnatural position and found it way more comfortable. It also made it possible for me to move a little (side or back). Cause if I sleep in the same position all night, my hips ache horribly.
To mix it up, I sometimes turn DS away from me so that I'm effectively spooning him, again with his head on my arm. This way I can have him quite low. I find this very comfortable.
Another thing I do when I get achy is that I turn onto my back and let DS sleep on his belly on my chest if that makes sense. in fact, this is how I co-slept with my babies for the first month or two of their lives. Somehow I felt safer this way. I felt like I couldn't roll onto them like this.

I'm a stomach sleeper. I miss sleeping on my stomach!! Sometimes in the mornings I hand DS over to DH for a cuddle and quickly turn onto my tummy - ahhhhh, bliss!
I'm pretty lucky. DS sleeps in his bed for large parts most nights these days...