I want to help my friend grow up a little is that bad?

Not at all.. You want the best for your friend!! That's being a good friend.. You know? Well, i don't know about the stuff your friend does.. So, i can't really give any advice on how to make her mature a little bit more.. It's all on you!! You seem like a good friend.. So, i'm sure you'll get it.. Well, good luck with your friend!