Huge egg drop in production, normal?

For a while I was getting 6-7 eggs everyday until the colder weather set in, which was around daylight saving time. I have a light in the coop that I keep on from 7am-6pm everyday. It's pretty dark in there without the light. We are putting a window this coming spring and rearranging the venting to go outside vs the garage. Our garage is covered in dust(DE) and hubby is not happy. We have 12 square feet of ventilation going into the garage. Our coop is built inside our garage and fully insulated with a radiator heater(we won't use until -22F times). It's a very nice set up we have for them. Our run is just outside the door and covered in plastic for the winter for the extra room. I have not free ranged in a few weeks due to hawks and they hate snow!

Anyways, my egg production has dropped to 1-2 eggs a day max! I'm assuming this is normal? They eat the same, plus they get fresh sprouts a few times a week. I'm seriously thinking of adding a couple more hens to the flock sooner then later. I'd die if we are forced to buy store bought eggs.