Help! $5k in and still struggling.

I want to start by saying please be nice, I'm so stressed out by how much money and time I've already spent on this. I'm just super frustrated and trying my best.

• 5'6", 125lbs, woman, side sleeper, narrow shoulders
• Current: plush mattress, queen size
• Previous: mistakenly bought a firm mattress, then a medium-firm mattress, and both were too hard for my hips, while my shoulders did not sink in at all. Tried a 2" memory foam topper, still the same issues (shoulders did not sink into the memory foam).
• What helped: plush mattress was finally good for my hips, and there is less pressure on my shoulder. Hurray! But, my shoulders still don't sink *enough* so there is still some pressure and my alignment is off (hips sinking more than shoulders).

As an experiment I put a folded towel under my neck and one under my waist (above hip area). This helped with alignment.

Part of me is worried the plush mattress is too soft, but I did try the medium-firm-plus-topper for a few months and it was still bruising my hip.

So now I think it's just an issue of "my hips keep sinking more than my shoulders".

What I'm considering now: 2" latex topper? I heard it could maybe help with more even sinkage (hips sink less but shoulders sink more?). I would try a zoned one but can't find a good one (I'm not in the U.S.) and I'm not even sure if it would help so I'm hesitant to spend that much.

I'm so burnt out after so much time at the mattress store, lots of money spent, and months of waking up in pain :(