Sofageorge, take that in mind: if she doesn't take the decision you would like her to take; it is not necessairly a bad decision. It might be on your point of view, but she could be very comfortable with it. Don't direct her into something. Like I said earlier, you don't have to suggest her anything or give her advices about what you think is right for her or what you think she is missing. The only thing you have to do is act like a good listner. Children's phsychology is very complex. I won't give you a course about that tonight but I think you are forceing her INDIRECTLY. You seem to agree she will make the final decision but you are influencing her just a little inconsiously. It's good to speak on emotional fields with her but do not guide the conversation the way you want it to. Just be a mirror of her feelings.
Example:
SG: Aren't you feeling lonely here in the states?
Girl: Yes, I miss my boyfriend a lot.
SG: You miss him.
Girl: yeah, I am affraid to lose him.
SG: why?
Girl: well, I don't want to lose contact with him because I don't want him to forget me.
SG: You think he will forget you if you stop calling him every day.
Girl: yeah, kind of. I would like to experience something new here and have fun but my boyfriend is really important to me.
SG: Your boyfriend is important in your life, this is why you are affraid to live something new here in the states.
.....................
Do you see where I am going? Let her speak. It will bring her to think back about what she is living. Only repeat what she tells you to show her some retroaction. Trust me. This is what psy do for 50$ an hour.