"Good morning, I am Kateřina!"
Translation:Dobré ráno, já jsem Kateřina!
It does not make sense. It mans: "I AM (indeed) Kateřina." (you remember my name correctly). It is possible on its own, but does not make sense with a greeting.
If you are just introducing your name, it is : "Jsem Kateřina." or "Já jsem Kateřina."
If you want to say that it is YOU who is named Kateřina here, you use: "Kateřina jsem já."