Hi soretom,
I’m sorry to hear that your mattress isn’t working out as well as you hoped for.
Unfortunately all the “bells and whistles” generally have more to do with marketing than with how well you will sleep on a mattress.
Unfortunately it’s not possible to “diagnose” mattress comfort issues on a forum with any certainty because you are the only one that can feel what you feel on a mattress and there are too many unique unknowns, variables, and complexities involved that can affect how each person sleeps on a mattress in terms of “comfort” and PPP (Posture and alignment, Pressure relief, and your Personal preferences) or any “symptoms” they experience so a mattress that would be “perfect” for one person may be completely unsuitable for someone else to sleep on.
Having said that … there is more about the most common symptoms that people may experience when they sleep on a mattress and the most likely (although not the only) reasons for them in post #2 here.
There is also more about primary or “deep” support and secondary or “surface” support and their relationship to firmness and pressure relief and the “roles” of different layers in a mattress in post #2 here and in post #4 here that may also be helpful in clarifying the difference between “support” and “pressure relief” and “feel”.
These posts are the “tools” that can help with the analysis, detective work, or trial and error that may be necessary to help you learn your body’s language and “translate” what your body is trying to tell you so you can identify the types of changes that have the best chance of reducing or eliminating any “symptoms” you are experiencing (at least to the degree that any symptoms are from your mattress rather than the result of any other circumstances or pre-existing issues you may have that aren’t connected to a mattress).
If the store where you purchased your mattress has an exchange or return policy then the simplest solution would probably be to exchange your mattress for a different one that would be a better match for you in terms of PPP … hopefully using the testing guidelines in the tutorial.
It’s certainly possible that your mattress is too firm for you and isn’t allowing your shoulders to sink into the mattress enough to relieve pressure and if this is the case then some of the suggestions in post #2 here may also be helpful. The most common solution for a mattress that is too firm would be adding a suitable topper.
If you believe that your mattress is too soft then it can be more difficult to “fix” but there are also some suggestions in post #4 here that may be helpful for a mattress that is too soft as well. I would make sure to try your mattress on the floor to see if it makes a difference in your symptoms or sleeping experience so you can confirm that the support system under your mattress isn’t the cause of any symptoms you are experiencing (your support system should provide the same firm support under a mattress as the floor).
Phoenix