Sounds good Jodi. Yeah you can place a small, firm pillow under your knees or a rolled-up towel. You can also put a smaller towel under your lower back. This will at least keep your spine in a relatively neutral position. Here is a product suggestion to support your knees when lying on your back. There are other similar products too:
https://www.amazon.com/dp/B07MZSTC1J
If you get to the point where you can sleep on your side, you can place a large yoga bolster against your back, and another one in front of you that you can rest your arm on. This provides a lot of support. And if you do sleep or lie on your side, you'll definitely need a firm pillow between your knees.

Feel better!

Joe