You sleep on your side and stomach and use the same amount of pillow for both?? Stomach definitely needs the least amount of cushion, except for people who use no pillow I guess. And side sleeping has an entire shoulder’s width of support to make up for. Totally different positions, you need an arsenal of pillows to really dial in the ergonomics.
I buy mine from the bulk store bc it’s like the same price for 500 pills vs 30 from a normal drug store. I never finish them before the expiration, but whatever