Thank you, also, for the ongoing review.
Was your old bed also memory foam? It would appear thinner pillows do better with memory foam. Since you sink into the memory foam, the pillow should not be too tall and cause undo stress on your neck and back.
You also might want to try an “adjustable” pillow like shredded latex or down. This has been something I’ve been researching for the past week as I am also a back/side sleeper. A lot of good information from forum members and resellers is here:https://forum.mattressunderground.com/t/natural-organic-vocs-pillows-and-otherwise The advantage is that you can adjust the height of the pillow throughout the night depending on how you’re sleeping.
As for softness, I am quite close in weight, age, and height and find firmness better for me. I have slept on and enjoyed a Tempurpedic Rhapsody and I originally set out to buy the equivalent from Tempflow or Select Foam and eventually decided on the Grandis from Select Foam (hopefully this extra splurging pays off). I do have (cause unknown) mild/light lower and mid back pain, though.