Overheating/coolant coming back out through the resovoir

What is your question?

repalced thermostat, did a pressure test on the coolant system for leaks and found none. Did a pressure test on the firewall port to the heater core and was able to see coolant rise in the resovoir. Lack of hot air inside the car. can't figure this out, anyone experience this? Bought a water pump with tool, but am not sure if that's the problem. No oil leaks and the engine runs really good so I don't think a head gasket is blown.