I have had my pitbull Zeus since he was 8 weeks old. He turned 4 on November 17th. I have never had any problems with him being aggressive towards the people he grew up around. He is very protective though.. and if someone he doesn’t know walks up to myself or husband or our kids he will growl and we have to tell him its okay ( something we did not train him to do). I had a pit bull named Sugar who we lost in October of 2009.. she was one of the best dog I have ever owned. She was never aggressive. She was protective of us as well but never growled would just bark. We picked her up as a stray ( we guessed she was around 2) I had her for 9 years and she never once showed any signs of aggression. A lot of stuff can be misleading, The way your dog behaves depends on how they are trained, raised and treated. I wouldn’t worry so much and please do not think that getting your puppy was a mistake. Give it a chance. They really are great dogs!