no one will notice this comment or will care... but if you're new and also thinking like those old comments about how "oh, why is she acting like she doesn't have the mind of an adult," or "she's acting weak, like she doesn't have years of experience,"
I'm sorry, have you time traveled before?? "MAN, what I would give to go back in time to my younger self and change things. I would do everything differently" However, it isn't as simple as that. Even in the present, whether child, teenager, or adult--we still have deeply rooted fears about the future and doubts that can hold us back, mistakes that we keep making over and over again. Even if you time-leaped back to the time where you wish you could've changed your actions the most, it would be something new for you since, as far as we know, time-leaps are not possible in reality. You might worry about whether your actions will really change your future, you will still carry the same insecurities and doubts that you had in your previous life that could still cause you to make mistakes. But that doesn't mean you're weak. It means you're human. Time leap or regular aging...it is up to you whether you want to stand up, make a move, change things for better future, or improve your self. Growth of character is not limited by age and won't immediately happen, even with one magic restart-button.
In addition, Shulli is basically on her own at this point. She has a life-time of memories, has to with a truckload of terrible baggage again that she never asked for, and somehow she has to organize a plan(RACK HER BRAIN, MAKE SURE SHE DIDN'T FORGET ANYTHING CUZ SHE'S HUMAN AND HUMANS FORGET) on how to make sure the past life doesn't repeat itself. What she went through was traumatizing for a young girl and she's scared to go through it again. But she's facing it head on, trying to push aside her doubts and fears, and doing things and changing things she never thought she'd be able to in the past. I think she's doing pretty good so far.