I want to know the difference between "concerned with" and "concerned about". I thought "concerned about" is correct here.
You're right, "concerned about" would be the correct form to use in this case. "Concerned about" means that you are worried about something while "concerned with" usually means that you are interested in something. So since she is talking about her worry here, it would have been more correct to say "concerned about" than "concerned with". A lot English speakers mix these two phrases up. Ex: I am concerned about her, she seems very stressed out. Ex: I'm concerned with studying plant biology.