Stop going to the dog park with her.
This may seem sudden but it's likely been building (and seems as though it was by her rough play). At 2 months in your home, she is just starting really settle in and show her full personality before it was like when you are on your best behavior when you first meet someone. Also, at 2 years old, she is just reaching maturity which is the age when many dogs are no longer as carefree as they once were.
Raven (GSD) - December 8, 2007
Kaiser (GSD) - November 2009
Holly (GSD) - March 24, 2011
Best Paw Forward