Is she worried about shortstop not being there? Is the shortstop there in time? Tell her if runner goes, she throws and if shortstop is not there then she (shortstop) will be the one getting chewed on. And then stick to it. If catcher throws a couple into centerfield because ss is not there, or worse yet, can not handle the throw, then that will definitely shake catcher and make her reconsider throwing. Good Luck.
I don't want teams to test my catcher after they watch her in warm-ups.