Hi drm870,
Thanks for taking the time to share an update … I appreciate it
Once you have gone through the initial break in and adjustment period then any further softening will be much more slow and gradual over a more extended period of time and it’s good to see that you are rotating your mattress as well to even things out.
Losing that much weight would also make a difference in how firm a mattress feels as well (foam mattresses will feel softer for those that are in higher weight ranges than the same mattress will feel for those that are lighter).
There is more information about support systems (bedframes and foundations or platform beds) that are generally suitable for different types of mattresses and some examples of each of them in post #1 here and some of the information and comments in this topic (which would apply to any foam mattress) may be helpful as well.
Phoenix