It might help you guys to remember that three things slow down when you lose weight:
(1) Resting Energy Expenditure because your body gets smaller, less tissue to maintenance.
(2) Resting Energy Expenditure because it does indeed slow as function of survival mechanism.
(3) Perhaps most surprisingly, non-exercise related energy expenditure slows.
Bottom line: you have to find a way to burn more calories either through calorie reduction (yes, you may need to go even lower), more activity (wear a pedometer if need be) or both.