The comsumption sounds a little high for a house that size. Check the usuals, including windows ducts etc, and make sure you are not heating your attic or something that you don't want warm. Also, have the gas guys check your regulator. We lived in Wisconsin and Minnesota for a few years, used propane heat and quieted down our bill by setting the 'stat lower. Usually, we kept the heat at about 55-58 and kept plenty warm. Of course you have to dress the bed a bit heavier. A side effect seemed to be that we never had a cold those years.