How to firm up my already firmest EOS mattress?

Hi! I am pretty desperate, hoping I can find help here. I wake up every day from back pain and have to get up, because I just can’t lie on this mattress anymore. When we were on vacation I had weeks without any issues. We were staying in a place with one of those super firm springy mattresses - where the surface doesn’t seem to give at all when you sit down. It feels super taught. I remember the original Ikea mattresses (Sultan?) where like that. In the 365 store they also had one mattress like it, their SOMA, but it was too firm for my husband. So we compromised on an EOS classic, so we could each have different firmnesses on our sides. Well, I have the extra firm coils and the firm latex and it is just too soft for me. I am not heavy (150lbs) but I just need a mattress I don’t sink into. Is there anything I can do to make my side firmer? We have a Thuma frame, so I don’t think the slats are the issue. I think it’s the coils not being strong enough or the latex giving too much, or both.

Hi Hanna and thanks for reaching out on this! Normally neither a firm nor extra firm topper will help beyond a negligible degree, even if you purchased a 3” extra firm topper. Support has to come from the mattress, not from the topper. Also, latex will conform to whatever surface it is on, so if your mattress is soft or sagging the topper will take on the characteristics of your mattress. Lastly, having a top layer that is not encased with the rest of the mattress will allow that top layer enough spatial freedom to move upwards when you lay on it, making for a very plush and enveloping feel, even if it’s an extra firm layer. About 75% of the customers that purchase a firm topper to make the mattress firmer end up returning it, that’s the only reason I mention these things.