Hi princessonapea.
Thanks for the added information and for taking the time to pinpoint the possible cause of your discomfort. Definitely 2 months is long enough to give a clear sense of mattress suitability.
Yes, having the central leg support is the best solution for any sagging due to slat flexing under the mattress weight and people sleeping on it. This queen foundation platform bed is made of Yellow/Tulip Poplar hardwood nicely built with the slat length is 27" for the left/right areas of the bed allowing only for minimal flexing. So placing the board on top of the slats may not contribute much.
All Luma hybrid lines have a 1" firm HD Base foam used for stabilization which would certainly prevent any coils to “fall inside” and slip between slats. As far as what to do next about your new mattress I suggest you contact Luma directly and see what they recommend. Given a summary of your experiences and eliminating some of the possible issues with the foundation… they’d be the first to tell you if the mattress reached the end of what can offer in your particular case or… based on your experience so far, they may come with an out of the box solution.
I’d pay special attention to the mattress “feel” you are looking for… especially in the comfort layer. Memory foam can be a “love it or hate it” material and it certainly has “weaknesses” that latex doesn’t have even though they are roughly equivalent in terms of cradling and their ability to relieve pressure.
With memory foam you would have a more in the mattress feel while with similar ILD in latex you would get more on the mattress feel because of the resilience (springiness) of latex without losing the cradling effect. Using latex may be better for the pains and aches you mentioned because it’s inherent supportiveness and ease to reposition throughout the night. Visco elastic memory foam is a delayed response foam and feels much firmer until it becomes softer with body heat and the feel is very different.
Another thing I’d pay attention to is the breathability and how “hot the mattress sleeps” Some types of memory foam are also more breathable than others and have less effect on sleeping temperature but memory foam, in general, tends to sleep warmer for some people than other types of foam materials (latex foam or polyfoam). There is more about the different properties that can be formulated into memory foam ~ post #9 here and post #8 here.
If you’re considering looking into with some sort of memory foam product, there are some guidelines for purchasing memory foam in post #10 here. There are some other memory foam brand options inpost #12 here . There’s also a bit about …how memory foam is made here .
Let us know what direction you chose to go and any questions that you might have.
Phoenix