Hi Munchie33,
Your description seems to differ from hotpink345’s, in that you’re describing not enough surface plushness or enough “bending in” to the deeper support core of the mattress. At least that’s what I’m inferring from your description. The addition of a softer comfort layer would “seem” to be a reasonable approach. You may wish to investigate some of these toppers that can be returned if you decide to go that route.
Phoenix