Mattress Configuration Help

I have recently purchased a latex mattress after sleeping on a firm mattress for the past 3 years. I am a side sleeper and I noticed that when I was using my hand a lot during the day either writing or using a mouse and keyboard, I would get a tingling/numbness in my pinky and ring fingers on both hands. I have recently come the conclusion that it is likely that since I sleep on my side, the weight of my torso combined with the firmness of the mattress was putting excess pressure on the nerve that runs through my shoulder and down into my fingers.

Unfortunately, the pain has yet to subside and I know that a lot of the members on TMU are very intelligent individuals that could possibly provide me with some words of advice!

My current mattress configuration is listed below, but I do have all of the layers split, which provides me with the ability to experiment!

TOP
Talalay Soft (19 ILD) 3"
Dunlop Medium (28 ILD) 3"
Dunlop Firm (38 ILD) 3"
Dunlop Firm (38 ILD) 3"
BOTTOM

I am 5,9" and I weight 165lbs

I was wondering if anyone would be able to provide me with some advice on what I should do ensure that I am getting enough support, but I am also relieving the pressure on my shoulder. Should I try and make my mattress softer with additional layers, or try something else? My only concern with adding an additional layer is the fact that I have already purchased a mattress cover that only fits 13". Thank you so much in advance!

-Alec