I have my mice in the garage and it is about 60 degrees in there now and I have great production, so temp is not that big of an issue IMO....as long as its 60-80..(room temp)...
Mice are strangely hard to breed...much harder than rats...What I did is I just put 1.2 per tub and left them alone...after almost 2 mos, they were all prego, and now I have consistent litters ever since....
In your case, if nothing happened since August, I would feed the females off and get 2 younger females....