Antifreeze leak

Oldmosbile Alero, 1999.3.4L V-6 89,600 miles

I am leaking antifreeze. I replaced the water pump 2-3 years back. I think I am seeing a significant leak from the head gasket. Would that probably be the source of my problem? Approximately what would it cost to replace that gasket?

The car is not overheating. Just emptying the reservoir almost weekly.

Thank you! Have a great day!