I need help because I don't know what to do?

My name is Tiffany...I was born Lutheran but since left the church and converted to Catholic. Well, I am coming to the end of my journey and getting ready for my confirmation (traditionally its around Easter but mine was special case). Anyway, I have been known as "Tiffany" for my whole life (25 years). My confirmation name is Anastasia. Now being newly Catholic and not completely understanding what to do, what name do I go by now?