Hi L.! Ugh! I hated that--I felt like I was so tired by day and then to have my sleep be unsettling...blehhh.
I'm too cheap to buy a special maternity pillow. I just used one of those pillows you throw on the couch. I used a small one though--12x12 and not too fluffy. It was easy to turn over and not bonk my husband when I switched sides in the night. The other thing my husband was willing to do was to put his back right up to mine like a wall and I leaned into it for support. (A best friend can do that ;=)--how wonderful for you to have such a great relationship!). Darryl was even willing to be woken up to "assume the position" if I needed it during the night.
I wish you only the best with the rest of your pregnancy and hope that you get this resolved soon. Do you have problems with the baby being active in the night as well?