Suffering and detachment
One way for people (especially children) to deal with their trauma is to become detached from reality. But as Frankie grows, her body's changes and the changes in her family cause her to overcome her detachment and try to connect with someone—a soldier, her friends, and her family. In this sense, she is the hero, because her attitude about life leads those close to her to overcome their complacent acceptance of the status quo.
Romantic desire and family desire
As a person of almost pubescent age, Frankie knows all too well how intimately the problems of romantic identity and family identity can be. So intimate, even your name feels wrong, and so she changes hers and tries to seek an alternate identity, trying to tag along on her brother's life with his wife, and trying to involve herself with a soldier. She wants to know what it means for her to have a place to fit into the universe where she can be loved. This drives her maturation.
Coming of age
By the end of the novel, Frankie is ready for the difficult life changes that are implied by moving with her dad. Readers can detect a considerable change from the Frankie at the beginning of the novel, when she couldn't cope with the change of her brother leaving the home. Now she herself is leaving the home. This is her coming of age, the end of a tender childhood, the beginning of her true adult experience. This makes the novel a bildungsroman.
