S.S.
You can stop her by not looking at her. She is getting ahuuge rise out of you and that will feed right into it so she can continue. I would hope she is talking and telling you what she wants by 14 months. If she is not, teach her signs so she will not be frustrated and find out why she isn't talking. Usually kids who headbutt are having problems communicating but I don't know the whole situation, just guessing.