Fanwer Positioning Wedge Pillow for Side Sleeping (3 in 1), 40 Degree Triangle Bed Wedges & Body Positioners for Back Pain, Preventing Bedsores, After Surgery, Knees Elevated, Pregnancy

I link this with a little hesitation, as I had a little wedge pillow that I bought in person so I was able to feel it. But really you’re looking for something firm. I found these support pillows that might help you. Unfortunately when it comes to stuff like this it’s mainly trial and error. Nothing is gonna work for everyone.