How can I add a bathroom fan to the existing end line light switch?
The answer to your only stated question is YES. To independently switch 2 different things you need to have 2 switched hot wires, you would have to run an additional wire from the wall switch location to the ceiling location.

The statement that "the light only has 14/2 running to the switch" tells us that one of those wires is a hot lead to the switch, the other is the switched hot that runs back up to the light (unless there are other/more wires that you did not mention).