I also think that she has GSD in her. My female, Sabra, was all ears as a baby and still has ears that are taller/longer than her mother's. Welcome to the forum. I have three words of advice - exercise and training - for her now and keep up with it. She looks wonderful.
Sabra - female GSD - born April 30, 2012
Sargeant - rescued senior GSD male/foster failure - approximately ten years old (August 2013)
Max - rescued GSD - Dec 22, 2010 to March 7, 2012 - at the bridge
Sable - rescued GSD - at the bridge