You do explain to a reader that this is a first chapter. Although it might seem incomplete to some, in my view, the conflict at the heart of the story is resolved. Will she go through with her plan to meet Harvey? Will she steal (borrow?) her foster father's credit card. The answer is yes. We as readers know this cannot end well for her. But the path is set. She's on her way. No turning back. This conflict is resolved as she puts down the groundwork for even greater conflicts.
Thanks for your feedback. It was an interesting experiment placing myself in the mind of a shy, awkward teenage girl and making her courageous.