Sound to me like you don’t have a double deep colony and they’ve stored all the syrup they want for the winter. They won’t fill an infinite space this time of year, even with drawn comb. Not only that, but they won’t have time to dry the syrup and cap it before winter. It sounds to me like what you have is a colony that doesn’t really fill even one deep. What I would do is winter in a single deep and insulate well (6 sides if possible) if you’re using wood boxes. A colony of bees that is really 1 deep (or less) does well over winter here in a well insulated hive.