This is a contemporary YA book and if you are trying to figure out what to do with an immature teen character, this book is perfect!
I mean that as a compliment. I wanted to strangle the lead from the start. By the end, she still has that fire and spark of adventure and freedom that can always lead to trouble, but her thought process is not the same and she DOES take into account those around her. It is an excellent example of a coming of age where the female character is slow to mature and hangs on to that youth and childish nature even when expecting to be treated like a young adult.
The secondary characters in a story like this are EVERYTHING. Study them. They are the catalyst to all of her developmental milestones. Some characters grow and change because it is time, they feel it, see it, know it. This one practically fights that evolution up until the moment she realizes who she is going to become and what that is going to cost her if she does not embrace the change. This means providing well-developed secondary characters and their profiles to the point that when the character has that Ah-Ha! moment, your reader is right there thinking, finally!