Hi kham,
It’s not unusual at all that a new mattress will feel firmer than the showroom model that you tested because there will be a break in period and you will also go through an adjustment period over the course of the first few weeks with any new mattress.
There is more about this and some other suggestions that may be helpful in post #2 here.
In general it’s usually best to “do nothing” with your mattress in the first few weeks (other than some of the other suggestions mentioned in the link) but if it’s clear that your mattress is still too firm then the first thing I would suggest is talking to B and L bedding about any options you have. Some manufacturers can change out the firmness of the comfort layers for a nominal charge but if that’s not possible then a topper can certainly be a good idea to add some additional softness and pressure relief.
If you do decide to add a topper then post #2 here and the topper guidelines it links to has some general suggestions about choosing a topper and the type, thickness, and firmness of a topper that may work best for you along with a link to a list of some of the better online topper sources I’m aware of as well (including Sleep On Latex).
Phoenix