2006 Pontiac Grand Prix Overheating

I have a 2006 Pontiac Grand Prix Base with 209,000 miles on it. It has had
an overheating issue over the past year, but started up bad again a few days
ago. Last year I replaced the thermostat, and water pump, and last month I
replaced the Radiator... does anyone have any idea of what could cause it to
overheat? I am thinking maybe its the head gasket? it doesn't smoke, no
fluid leaking under the hood, but it is definitely going through antifreeze quite
frequently. I don't know if there is a common issue that could be fixed
relatively easily or if the car is just getting tired and I should move on. thanks
for any help in advance