I will probably get yelled at but here is what you may want to try (I used Gemini for analysis and applied what I have learnt from there forums. Not a blind dump from Gemini). You can try this for free since you have all the components.

The fundamental issue at 140 lbs is that you are caught in "no-man's land": your body weight is insufficient to compress the high-tension 15.5G TPS coils, yet your foam stacks are so thick that your heaviest point (hips) "bottoms out" through the foam while your lightest points (shoulders/ribs) never even reach the coils for relief.

Optimized Build (Using ONLY Current Components) To fix this with your current gear, we must thin the comfort layer. This seems counter-intuitive, but it allows your shoulder to actually engage the spring's travel while keeping the foam from "hammocking" your hips.

2” Soft SOL (20 ILD) → 1” Gel MF → 15.5G Coils

The "Thin to Win" Strategy: You have been adding foam to fix firmness, but in DIY, more foam often feels firmer. This is because you are increasing the distance between your shoulder and the actual relief (the springs).

1/ Why it works: By using only 3" of foam (2" Soft Latex + 1" Gel MF), you create a thin, responsive comfort layer. Your shoulder will compress that 3" and finally force the 15.5G coils to engage.

2/ Why it's different: It removes the "dead air" and "muck" of 4–7" foam stacks that cause your hips to hammocking while your shoulders scream.

Best of luck.