Good for you! I always like to see winter commuters. Winter riding is slow and hard. Air is more dense, and when it gets really cold, your grease can solidify, making you even slower. Synthetic grease will give you a fighting chance of staying liquid. Tires, especially the studded ones, also contribute to slowing you down. You'll sure be fast in spring, though.

I would suggest adding another fleece or wool sweater, and losing the windbreaker (moisture trapper) altogether. If your average speed was 12 km/h, the windbreaker is probably doing you more harm than good. If I had enough time, one sewing project I've had in mind for a while would be to add windproofing patches from an old coat to an old fleece shirt, only in the areas that need them (upper arms, chest and stomach for me), leaving the rest breathable. You could probably ditch the goggles too, but I'd suggest adding a half-mask or balaclava style that covers your cheeks.

For feet, say yes to loose shoes; you need air in there to stay warm. If you're riding with clipless, try some insulating insoles ("toasty feet" at Wal-mart might be thin enough?; I bought the thermal insoles Mark'sWork Wearhouse sells, but they made my shoes too tight. If my shoes had been one size too big they probably would have worked. I wore them with my husband's shoes (2 sizes too big), and they were great); the metal plate steals a lot of heat. I also find plastic bags over my socks cut the wind and keep my feet warm. There are also chemical packets and battery powered socks you can try (Canadian Tire, Mark's) if insulation alone isn't working for you.