I read this story a while ago but can't remember the name.
It s an edwardxbella story and Bella has some sort of disease that she has been fighting since she was younger. No one knew but Charlie not even Edward and they did not find out till Carlisle is transferred to the clinic that Bella is getting treatment at. Also Leah's imprint is in the clinic for the same reason as Bella. Only after the rest of the family find out does Bella tell them that she is fighting to live past her 19th birthday, the doctor treating her is also a vamp and can tell when people are going to die.