Need your advise for extra layer

Hello sleep ez
I diy my mattress using your toppers and latex mattress factory toppers which I found out your sister company. I am 5" 2 and 138 lbs, side sleeper. My husband is 6" 2 and 170 lbs, side and back sleeper. I bought 8" coils from latex mattress factory and 2 layers of latex from sleep ez (3" soft Talalay and 2" medium Dunlop). It’s been a week. It was perfectly fine and comfortable first 5 days but last 2 nights I woke up with back pain. I still have room in my envasement to add another one or two inches (my envasement cover was customized 13 inches but I believe it is little over 13 inches). I need your advise on the layer that I should add to relieve my pain. Thank you