Could be water pump yes. Look where the water pump shaft is and see right behind where the shaft enters the pump and see if you see a small hole on either side of the pump. See if there is any anti-freeze coming out of the that hole or anywhere around the water pump housing. If you see anti-freeze coming out then the pump is probably bad and needs to be changed. You could also be loosing it from the heater core although most of the time you will notice a substance on your inner side of windshield that when you try and clean it only smears. Looks like a film on the windshield inside of the car. You will also smell anti-freeze pretty strongly inside of the car especially when you use your heater.