Fly back, Agnes / Elizabeth Atkinson.

Enhanced descriptions from Syndetics:

A heartfelt story that sensitively tackles the everyday inner turmoil of growing up and staying true to oneself.Twelve-year-old Agnes hates everything about her life: her name, her parents' divorce, her best friend's abandonment, her changing body . . . . So while staying with her dad over the summer, she decides to become someone else. She tells people she meets that her name is Chloe, she's fourteen, her parents are married, and she's a dancer and actor--just the life she wants.But Agnes's fibs quickly stack up and start to complicate her new friendships, especially with Fin, whose mysterious relative runs a local raptor rehab center that fascinates Agnes. The birds, given time and care, heal and fly back home. Agnes, too, wants to get back to wherever she truly belongs. But first she must come to see the good in her real life, however flawed and messy it is, and be honest with her friends, her family, and herself.