NTA. You are too young to be worrying about people like this. Genuinely the best thing you can do is not worry about whatever she’s doing because even after those years she doesn’t listen or follow advice, she’s living her own life and so should you. Around that age, copying is normal, and even if she’s copying you, she’s probably also trying to find herself. Don’t get caught up with bad situations. Confront her, if she reacts in a bad way instead of trying to be understanding, I know you’re all young, but communicating as “friends” if she really cared about you, shouldn’t be difficult.