>#1 - I'm 17 (9 months til 18) is there anything she can
>really do to keep me from living with my dad?
No. The court would never force you to live with your Mom at this point, because the judge knows, that you could just get up and go back to your Dad's, so the order would be unenforceable.
>#2 - What if I do it anyway? What can happen?
Court could make a specific order instructing you to stay at your Mom's, and failure would mean a trip to juvenile hall, or to a foster home in some other part of the city.
That's a worst case scenaro, which, while legally possible, is inconceivable in practice. If you were 13, maybe, but not at 17 3/12.
The only reason to file a motion to legally change the
court order so as to recognize father's primary custodial responsibility, is to have child
support changed.
But, if that's not interesting to your father, then spending money in court just for a legal change is probably a waste of time.