Replacement King Mattress

I have read thru the education materials a couple of times and get a little lost in some of the details, but I thought I had a fairly decent grasp. I got a King Size Denver Mattress Doctors Choice Elite Plush. Now have back pain all over and toss and turn all night. I still have 30 days to swap it out.

I am over 300lbs and need the right support layers and from my notes maybe this one might work? My previous mattress was traditional memory foam and kept it was too long and had lower back pain for quite some time. I am primarily a side sleeper.

Thank you for any input you can share!

Telluride Medium Mattress King Size from Denver Mattress

Quilt Layers:
Knit zippered cover featuring ICE yarn and PCM cooling Technology
FR Sock

Comfort Layers:
1" Copper Infused 3lb. Visco Foam Topper
2" Talalay 100% Natural Latex
1" 19 gauge Micro-Coil (2226 Coil Count for Queen size mattress)
Laminate Insulator

Support System:
952 Individually Wrapped Coils (Based on Queen size mattress)
2" High Density Base Foam