Hi jbeau, and welcome aboard!
I can totally relate to the aging fast thing, since it happened to me too because familly problem required me to be an adult when I was only 12 or so. Actually, it's not the situation that requires it, it's sadly the parents failing to act as adult parents protecting their kids instead of half children relying on their own kid as if they were adults... but I only realised it far later. Even in the worst situation, responsible parents will make sure never to ask from their kid what our parents asked from us - I've seen single parents going through real hardships, yet their kids had a real chidhood and could develop like any kid should.
I'm saying that because the after effect for me was a really hard time when I was around your age. Not having been able to experience childhood+adolescence hits you in the face round 20-25 years old. Even if you're sure you're more adult than people your age (like I was convinced), some preemptive counseling sessions can prevent the worst. I made the mistake to assume reading books and looking by myself was better than another human being's input, and I can tell you it's not enough - it has nothing to do with "knowing". I'm saying that because you seem to have also been looking really hard for something.
As for the Witnesses, I encourage you to really do your own research, and question everyone, even on this board. That nice young sister sure was convincing, as I sure was to young sisters (and young brothers) when I was pionneering, also convinced of my objectives and the value of pursuing "spiritual" goals. Let me tell you, how I wish I had had internet at the time, and could have checked for myself what the Watchtower says in its publications, realise the misquotations and the blatant lies.
Oh, and that "us vs them" mentality? That's 100% the sign of a high control destructive group. Don't trust me, read Steve Hassan's books, or have a look at other cults - the Family International, the Mormons, Scientology, etc...
I wish you well on your journey. Who knows, maybe you could even help that nice and zealous girl to realise how tricked she's been by the Watchtower, and not waste her life like she seem set upon to do.