Ok, to check to make sure your water pump is working: take out the thermostat then put the housing back together and run the car without it and keep the radiator cap off and look in. If you can see coolant flowing, your water pump is working.

The best way to check the headgasket is a leakdown test. You pressurize each cylinder and listen/look for escaping air. On my car, the air is escaping into the coolant passages and making the coolant bubble from the radiator cap opening. You have a new headgasket, but if it's not torqued down enough or not sealed fully in one spot, it's gonna leak.