Yes, cruising the week before or after the week of Thanksgiving would probably be best as far as minimal childern goes. Those weeks would probably be less expensive also.
You are still outside of the "no refund" window, if you can get the extra vacation time, call the travel agent back and see if you can move your cruise. Except for airfare possibly, there should not be a charge this far out to move you dates.
If your TA gives you grief about, find another one because that would definetly not be a cruise friendly TA...
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007