Do you think you grew up too fast?

In some ways, I did. I also had a dysfunctional family. And I went through a cynical, jaded period too, but thank God it wasn't that long. Cynical, jaded adults ARE immature, in my humble opinion. It sound perhaps like you are indignant that your peers are able to behave like kids and you haven't had that luxury. One of the most important thing you can hear from me is that, while your rough childhood may have significantly contributed to your negative, bitter stance in life, you are fully capable of choosing to handle things differently. If you are still in school, I would strongly encourage you to start meeting with your school counselor to start working through the ugly stuff from your childhood. You still have the chance to not only be a much healthier adult, but you can also have a much healthier adolescence. Best wishes to you.