Like some mentioned before, I also think that main girl is reaching the point where she is going back to the (new?) future. The nearer she gets to that point she will slip more frequently between the past and her future. Like Schrödingers Cat, taking a superposition, being in two time points/possibilities at (nearly) the same time.
If her future was altered by her actions is another debate
Well, she didn't actually "disappear" from the future, since with the past changed the even that led to that likely never happened (or not resulted in time travel, since she no longer needs to fix the past), so yes, only here memories go back and forth, she actually exist in both places.
I think she's working in a different place now, her "atmosphere" feels a bit different, and it seems like her "old" self doesn't recognize her workplace, so its probably a different job, then what she had back then.