HI atomheartmother,
I’m glad things have improved. People often underestimate the importance of the surface upon which their new mattress is placed.
All foams soften a bit over time, and with any new mattress there will be a loss of the initial “false firmness”, mostly within the first 90 days or so, and the more gradually thereafter. To help even this out, you can try to use as much of the mattress as possible so that it “breaks in” more evenly.
The latex used in the upper layers of your mattress will have an instant response back to resting height, but there could be a slight recovery of the quilted polyfoam and fiber in the quilt panel as the day goes on. Also, there will be even more “loft recovery” in any poly filled quilting you may have in your mattress pad as the day goes on as well.
Some body impressioning is normal, and your warranty allows for up to 1" of impressions before it can be considered a defect in materials.
Your body won’t sink in much more throughout the night than when you first get into the mattress, as there are no viscoelastic (memory foams) present in the mattress than become softer (less viscous) with your body heat through the night. The latex and the polyfoam core beneath generally stay quite consistent. If a mattress is too firm for you, you don’t want to sink in more in the deeper areas, as this would negatively impact alignment. Your better option would be the addition of a topper or change to slightly softer upper comfort foam layers.
Brooklyn Bedding does have a topper line (mattresstopper.com). There are also some topper guidelines in post #8 here that you can use, and some of the better sources for toppers of which I am aware are in [url=https://forum.mattressunderground.com/t/foam-factory-any-good]post #4 here[url].
Phoenix