How are you storing the paper now? It strikes me that Rich and I are using more that just the standard packaging to protect the paper between printing sessions. I print more often than you but not with every paper I have in storage. Some of my papers are 6-12 months old but they are in light tight drawers or paper safes. Could that be the problem for you? Maybe refrigeration/freezing will work for you, but I have not had one sheet go bad in the four years I have been using this darkroom. The other day I even tried some Polymax FBVC that had been sitting in a paper safe since Kodak discontinued it. How old is that 3-4 years? I don't remember. All those rumors that there was a built in developer that would pop out even if you froze it have not fogged this box of 16x20.
Trying to help.