Im having the same exact problems for the past few weeks 20-24 or so...I have been putting a squishy feather pillow under my belly and in between my legs, laying on my left side most with another pillow under my head and my arm behind me in the recovery position (any other way it puts too much weight on my shoulder and my hands go numb).
This has been working for me so far without the mega body pillow becoming a fourth party in our bed!!