Simpsonia:
I'm sorry to hear about your back issues.
First off, a disclaimer. I can't diagnose any sort of back issue via an online forum, and if anyone else purports to possess that capacity, in the words of Monty Python, "
Run away! Run away!
!" The best I can offer is some general guidance.
By far the most important thing I would suggest would be to get a good evaluation from a healthcare professional who specializes in orthopedics. Having back pain for 10 years is quite a long time, and if there's a physical reason for the pain it certainly would be something you'd want to know about. Perhaps it can be addressed with specific flexibility exercises, strengthening, manipulative therapy or some other remedy. That would be the most important thing.
As for the mattress, I wish there was a certain item that would address/cure all low back pain - wouldn't that be wonderful?! It seems that you prefer something with a bit more surface tension, but still something that allows for some conformation while on your side, and still keeps you in a relatively neutral alignment. There are multiple ways to accomplish this, including a few that you mentioned. Latex certainly has good point elasticity, and in a slightly firmer uppermost layer it can still provide some good surface tension. You can also accomplish this with some pre-compressed natural fibers, such as cotton or wool, which you also mentioned. Higher density polyfoams that aren't ultra plush might also do the trick. All of these in the uppermost layers might be helpful to you, and you'd need to make sure that the materials beneath in the deeper upholstery layers were substantial enough so that they don't allow too deep of a comfort cradle nor do they lose their support factor too quickly. This would generally be materials of a higher density.
Regarding your experiences with your other mattresses, I can make some guesses:
(1) Was probably too hard to begin with, and then adding the memory foam topper would certainly have provided softness, but not something with a very good support factor. You more than likely would have been better off with a latex topper, maybe something that is 3" in the mid 20s ILD or so.
(2) New mattresses generally don't change too much in just one week, especially ones that are compressed and shipped as roll-packed items (they do tend to get a bit softer as they wear-in). I'd hazard a guess that is most likely your body adjusting to a new mattress and spending more time in one position as time went on, exposing your back pain issues. The extra topper comfort material on top may have exacerbated your alignment issues.
(3) Mattresses with a harder surface comfort do tend to be more appropriate for back and stomach sleeping and not as much for side sleeping - that is true.
Again, these are just guesses, and the common theme here is you and your back issues. You really need to start with a diagnosis of that and then begin to move forward from there. Even if you walked into my showroom today, I'd be hesitant about selling you mattress without more information regarding what you actually have going on, as you're describing two different issues. One is pressure points, which generally tends to be more surface plushness related, and the other is back pain, which generally tends to be more alignment related. These can be two very different things to address.
My answer probably isn't the one you wanted to hear, but it's the best I can offer, even with my background in biomechanics and anatomy. Maybe someone else in the forum has some other advice that might be more helpful.
Good luck!
