Best tension for me latex

Hi, I am looking at your latex mattresses.
I am a 100kg, 5ft 7 curvy lady, who sleeps on my side. I am currently using a firm John Lewis luxury 2500 pocket spring by Harrisons, which feels like an uncomfortable brick, even with a memory foam and a wool topper. I wake with lower back pain around the waist and shoulder pain. Which takes an hour of yoga or swimming a day to fix!!
Would I be better with latex sprung, if so, what tension, or pure latex?
Many thanks