TPS 14.75 vs 15.5 quad coils - need slightly firmer than Sealy, 7", 1117 count, 15 gauge innerspring

So far down the rabbit hole, hoping to get some advice.

I’m currently using a Sealy, 7", 1117 count, 15 gauge with a 16 gauge “coil edge system” which is basically two smaller coils along the boarders, king innerspring that I removed from a 5 year old mattress for my DIY. I feel like I’m not getting the support I need from the coils and have been consistently waking up with back pain. I’d like to upgrade the innersprings and spent most of the weekend looking at reviews / posts to try and determine the right gauge for my height, weight and sleeping position. I’m 6’1, 215lbs and a side sleeper. I’m right at the numbers where TPS says I can go either way… and the posts I’ve read all say the same… some say the 15.5 is too firm, some say it’s too soft, some say the 14.75 is too firm, etc…

From my reading if I understand it correctly, the TPS, 1224, quad 8" should be firmer than the Sealy due to the way they are manufactured, but looking at the numbers, 15.5 is a thinner gauge than the 15 I currently have.

I’m currently using the 7" Sealy, a 3" medium Talalay from SOL and a 3" mattress pad which is more like 1".

I’m leaning towards the 14.75 but most of the reviews say to stay with the 15.5. But I’m worried it will be as soft or softer than the current coils I’m using.

Any thoughts or suggestions? I’m going to try to reach out to Matan tomorrow, but thought I would post in the meantime to see if someone may have some suggestions. TIA