Hi Maddog29,
Thanks for the update! I’m happy that things are moving in a better direction for you and going to a slightly firmer upper layer (28 vs. 19 ILD) seems to be working out.
There could be multiple reasons for the slightly firmer layer working better. If the 19 ILD could have allowed you to “sink in” a bit too much and it could not have supported your torso enough and this could have placed most stress upon your shoulders. It also could have caused the issue that you stated of allowing your shoulder to rest in an awkward position. It also could not have provided enough surface support for you.
There really is no one best ILD or combination of materials that are best for side sleepers, so at least on this site it’s more of an explanation of averages, but then reliance upon your own careful personal testing. There isn’t a formula that can predict with any certainty what type of layering you may do best with that can possibly be more accurate than your own personal experience and without this the next best way to decide on the design of a mattress is to use the “averages” of a manufacturer for people of your weight range, body type, sleeping style, and personal preferences. These “averages” may vary from manufacturer to manufacturer depending on the specific designs and options that they have available (including all the components such as the cover or quilting layers which can also have a significant effect on how the mattress feels and performs not just the latex or foam layers).
Using a little bit of a firmer layer on top is something that I discuss frequently on the site – what I call dominant layering. But again this would be only as general guidance and not an absolute as to what would be best for every individual.
I’m looking forward to your future updates, and I hope they’re positive!
Phoenix