Please help with mattress replacement

In 2011, I bought a Pure Talalay Bliss Beautiful latex mattress to address my back, hip and shoulder pain after sleeping on too-firm spring mattresses and previous lower back surgery. I’m very large female, 6’ tall with an athletic build, and my weight will range between 180 - 195 lbs. I do a lot of strength work due to my aerial arts hobby, which means that my shoulders are often tight and tired. For about 7 or 8 years, the Pure Talalay Bliss mattress was great, but I noticed visible sagging in the middle over the last two years I had it and started waking with some lower back pain. In June, I replaced it with an all-latex Naturepedic EOS mattress after trying all their models in the store. I settled on all-latex as my previous experience was generally good and I can actually feel the springs through the latex in a hybrid mattress. I used all the techniques from Mattress Underground, taking photos of my back alignment, testing for pressure relief, but have never found any comfort with this mattress. Even after 30 days, the mattress feels much firmer than the models in the store (which I discovered had been replaced in May). I originally purchased a M-M-F/M-F-F split configuration bed (sometimes I roll onto my stomach) and placed this directly on my slatted platform bed, which I validated and bought specifically for the proper support of a latex mattress. Due to hip pain and shoulder numbness, I later swapped out the M-F-F to S-M-F. I still had minimal relief. I then bought a two-inch talalay topper (trying both medium and soft) from SleepEZ over this Naturepedic mattress. I found a bit more relief, but not much and I still feel pressure points at my hips and shoulders. I’m wondering if it might be due to the cover, as I can literally feel stiffness under the Talalay topper. I’m ready to return this mattress and feel frustrated as I don’t understand how the experience could be so radically different from the store models. I’m also unclear why this is so difficult.