1997 Honda Civic Coolant Loss

I have been noticing that when I get to my destination there is smell coming from the engine compartment. I checked the coolant reservior and notice it is empty. I have been adding coolant and losing coolant. My temp gauge is OK except one time when I was stuck in a traffic jam and the gauge went to the hot zone. My oil level if fine as well as the color and I recently had my water pump replaced and timing belt.
There is no coolant on the ground. I do notice that there may have been coolant splashing near the resevior container. I am hoping it is not the manifold gasket since that is expensive. Also is constantly filling the coolant resevior bad for the engine.