What is katniss' greatest fear after her private session with the gamemakers?

Answer 1

She is worried that they will give her the first ever zero in 75 years!! She thinks that if she gets a zero that it will be the end, no one will sponsor her and she will surely die in the arena with no sponsors!\

Hope this helps:)

Answer 2

In Catching Fire she is scared her actions will turn the gamemakers on her and Peeta. She thinks they will make their time in the arena harder than it should have been and that it will be harder for her to keep Peeta alive.