Yoooo I dont know if i get in trouble for posting an amazon link in here but i will take the chance. Literally life changing for me. Suffered from back pain for many years would wake up 5+ times a night to change position then i discovered this pillow. Give it a try, its cheap and waaaaay worth it imo. Might take a couple of days getting use to it but believe me when i say it changed me. I know travel with damn thing lol
https://www.amazon.com/gp/product/B01A8TPWS2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
I bought this one from Amazon and really like it.
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Cushy Form Knee Pillow for Side Sleepers - Sciatic Nerve Pain Relief Leg Pillow - Best for Sciatica, Pregnancy, Hip, Back and Spine Alignment - Memory Foam Orthopedic Contour Wedge with Washable Cover
by Thera Health Brands
Learn more: https://smile.amazon.com/dp/B01A8TPWS2/ref=cm\_sw\_em\_r\_mt\_dp\_U\_kMoAEbVXRBEVC
I recently switched to my side and back (I preferred the exact stomach position you described) due to back pain and this pillow has been great.
Check amazon for an orthopedic knee pillow. I use this one with good results
Cushy Form Sciatic Nerve Pain Relief Knee Pillow - Best for Hip, Leg, Knee, Back and Spine Alignment - Memory Foam Orthopedic Leg Pillow Wedge with Washable Cover + Free Storage Bag https://www.amazon.com/dp/B01A8TPWS2/ref=cm_sw_r_cp_api_i_8Xj4Ab8WRWMTT