Engine cooling issues

My engine of my 89 chevy celebrity over-heated the other night. We found a leak in the lower radiator hose and replaced it. Only to discover that it was spraying water from a busted gasket near the hose near where teh hose connects to motor, but wasnt leaking from the hose. Not sure if the gasket was to the water pump or not since I know very little about cars. We replaced that gasket and had no leaks. We also went ahead and replaced the thermostat since we found no leaks we thought myabe the thermostat had gotten stuck. We refilled coolant and it ran fine with exception that it gurgled water back into the overflow tank alot not sure if that is normal or not, we also checked to see if there was water in the oil and there was none. The next morning I checked the coolant levels and the overflow tank was completely empty when car was cold. Also the radiator only was only about 1/3 of the way full. There dont appear to be any leaks anywhere when it is running or when it is not running. So im not sure what is causing it to burn so much water/coolant. Its been this way for the past 2 mornings that ive checked it. There is no discharge of water from the exhaust and no apparent missing in the engine. Can you please tell me if this is normal or what could be causing this and if it isnt normal what needs to be checked in order to fix it?