2004 Grand Prix gt2 overheating. Water pump replaced recently.

A couple months ago my 2004 grand prix gt2 started overheating. I took it to the shop and they said it was the water pump. Therefore, I had them replace it. The car has ran fine since then but 2 days ago it started overheating, checked the coolant and it was empty. Filled it up and then today while on the highway it started smoking, alarmed me that it was overheating, traction control shut off. I stopped and put more coolant in it, then drove it to park, after letting it sit for a while. Now the check engine light is on. Does anybody know what this could be? Also, I have not noticed any coolant on the ground or anything to see that its leaking. Thank You