Hi Eido,
If you ask them for a recommendation they will be happy to provide it but there are many people that just order a mattress without asking for any guidance or recommendations so it would depend on whether you asked when you talked with them.
I would also keep in mind that there are no “standard” definitions or consensus of opinions for firmness ratings and different manufacturers can rate their mattresses very differently than others so a mattress that one manufacturer rates as being a specific firmness could be rated very differently by another manufacturer. Different people can also have very different perceptions of firmness and softness compared to others as well and a mattress that is firm for one can feel like “medium” for someone else or even “soft” for someone else (or vice versa) depending on their body type and weight, sleeping style, physiology, their frame of reference based on what they are used to, and their individual sensitivity and perceptions. This is all relative and very subjective and is as much an art as a science. There are also different types of firmness and softness that different people may be sensitive to that can affect how they “rate” a mattress as well (see post #15 here).
For example a person that is heavier may sink into the mattress more deeply and feel more of the firmer layers that are deeper in the mattress while others that are lighter may only feel more of the softer layers that are closer to the top of the same mattress. In the end the only reliable way to know how firm or soft a mattress feels for you or how it compares to another mattress will be based on your own testing or personal experience regardless of whether it feels firm or soft to someone else or how anyone else may “rate” it compared to other mattresses as well.
You are also the only one that can feel what you feel on a mattress and there are too many unknowns, variables, and personal preferences involved for anyone to be able to predict or make a specific suggestion or recommendation about which mattress would be the best “match” for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) based on specs (either yours or a mattress) or “theory at a distance” that can possibly be more accurate than your own personal testing or sleeping experience (see mattress firmness/comfort levels in post #2 here).
I have also never slept on the mattress you purchased so I have no idea how any of their firmness levels would feel for me much less for someone else that may be very different from me so I certainly wouldn’t be a reliable source of guidance.
When you can’t test a mattress in person then the most reliable source of guidance is always a more detailed phone conversation with a knowledgeable and experienced retailer or manufacturer that has your best interests at heart (such as Dreamfoam) and who can help “talk you through” the specifics of their mattresses and the options they have available that may be the best “match” for you based on the information you provide them, any local testing you have done or mattresses you have slept on and liked that they are familiar with, and the “averages” of other customers that are similar to you. They will know more about “matching” their specific mattress designs to different body types, sleeping positions, and preferences than anyone else (including me).
There is 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 differences between “support/alignment” and “comfort/pressure relief” and “feel”.
There is also more detailed information 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 and while I don’t know your weight or body type … based on your description of lower back pain the odds are very high that your mattress is too soft for you but they are the ones that will be in the best position to help you decide which of their firmness levels would have the highest chance of success.
Phoenix