How can I learn my Haftorah for my Bat Mitzvah in time?

Yes calm down, when I had my Bat Mitzvah I didn't learn my Torah or Haftorah portion until a month or so before my Bat Mitzvah. Just practice getting in a rhythm with it and as my rabbi told me don't worry about messing up because no one will probably know anyways (granted I am reform so it may be different for you). I might up the practicing a little bit though until you start getting more progress. best of luck though