You might check with your TA, he/she might be able to find out from Princess how full your cruise is. The Princess site does not have that info. Actually, one day recently I was home recouping from dental surgery & had some time on my hands. So while I was web surfing I went to travelocity.com & pretended that I was booking. I brought up my cruise & I saw what cabins were left unbooked. I've done this several times since & noticed that the cabins seem to change from day to day as some cabins are on hold one day & go back on sale the next. But it did give me an idea of how full the ship will be.
Why can't you call Princess direct @1-800-PRINCES(S) and ask? We booked direct thru Princess, and there is a message to key in a certain number for existing cruises. Maybe that is only for people that book with them, I don't know. You will need your reservation # definitely. I got our cabin assignment that way.