Hi lebaryo,
If your mattress was a thinner layer of soft latex then it may have been firmer than you think. Thinner layers and thinner mattresses get firmer faster as you sink into them than thicker layers and mattresses so even a thinner layer of soft latex can be quite firm once you sink into it (see post #14 here for more about the effects of layer thickness). For example a 4" layer of soft latex could be very firm for some people.
If it also just had a sheet on top of it then I’d definitely try removing the protectors and unzpipping or removing the cover to see what difference it makes.
I would go slowly when you are making changes and take things one step at a time.
Phoenix