Exactly. There's every possibility that the flow of time as we 'expect' it to be doesn't even exist. Perhaps the reason Kat saved Annie is because she did - maybe what we are interpreting as a 'loop' is simply a fixed point in reality that has no beginning or end. Most importantly it probably doesn't matter - the story is going to explain things however it feels like doing and everyone's personal opinion on how time travel 'should' work isn't really going to matter.