Hi Mstrlucky74,
I don’t know the specifics of the materials or construction of your couch (which tend to be thinner and firmer than a mattress because it’s designed to hold up more concentrated weight) or your mattress so while the difference between them is pointing to “something” … there is no way for me to know what it is without having more specific information about both your couch and your mattress.
The only two ways I know to choose a mattress is either based on your own careful and objective testing using the testing guidelines in the tutorial post or with more detailed conversations with an online manufacturer or retailer (see mattress firmness/comfort levels in post #2 here).
I’m happy to help with “how” to choose, to help identify any weak links in a mattress, or make some comments about the quality of the materials or construction of a mattress, but the specifics of “what” to choose can only be decided by each person for themselves based on the parts of their personal value equation that are most important to them since there are too many variables, unknowns, and personal preferences involved for anyone else to know which mattress is best for you…
Phoenix