Yup I also use similar u shape pillow recommended by M and Anonymous. On some days strangely though, using it makes my back ache more. So just be in tune w your body, certain days the pillow is useful while certain days it’s not . Not sure why. What always worked for me however is placing a flat, low pillow at just below knee area to support the weight gravity (=pressure) coming from my heavy tummy. You need to observe your own body, play around with different height pillows to cushion at different parts of your body to experiment what is most comfy for u. Sometimes it’s at your back, sometimes buttocks, sometimes legs.
I got this from Shopee too! https://shopee.sg/product/296299147/4967944759?smtt=0.30516520-1640615615.9 It has a Velcro so you can adjust the distance in between the pillow to make it comfortable and more suitable for you. Can also remove the extra pillow if it gets in the way. :) I actually removed the small pillow cause it didn’t serve a purpose for me. If I do happen to end up on my back, I’m somehow elevated on either side too. :)
i got something like this one from taobao: https://shopee.sg/product/237464418/6957332798?smtt=0.354722587-1640604896.9 it helps me a lot during sleep and keeps me on my side more too. plus not so bulky
I got the clevamama one that can transform to a sleep pod for bb when born, its pretty good