Richie, you would make a great pet sitter but as a "Professional" Pet Sitter myself, I can tell you that at your young age, you probably won't get much business unless it's from friends and neighbors. Seriously, I am bonded and insured and people are still nervous about having me (a stranger) coming into their homes, until they get to know me.
I used to work in a kennel too and I know that the owner has hired someone as young as 13 so you may want to look into it. They probably wouldn't just let you volunteer because there is a liability issue. The same is probably true for shelters, but I'm not sure.
I'm sorry your parents are so primitive in their ways of thinking that it's "just a dog" because I sense that you REALLY want one. For sure, though, a Pit Bull would definately be the wrong breed to start with in your situation.
Is there any way you could take full responsibility for a dog? Lots of people work 10 hours a day and still have time for their dogs. Could you lay down some rules for your parents? I think any dog would be lucky to have you as its' owner/companion and I hope you find a way to get one and make it all work out. I've had dogs all of my life and can't imagine life without one.
You've said you've decided to wait....but I can sense how sad you are...and disapointed...
Pam