2004 Intrepid, missing coolant and no heat!

The coolant needs to be topped off pretty much every time you drive it, even if you just let it idle. I cant find any spots, leaks nothing. Not sure if its related or not, but the heat also doesn't work in the car. Im assuming its a head gasket going out, but the heater is what throws me off. Could they be related. Just need more mechanically inclined minds to possible help and hive me some ideas to what could be going on. Thanks in advance!