She looks pure to me too. My girl Jamie had real short fur when she was younger. She did not get her longer coat until she got older. Any way about it whether she is mixed or not she is a real cutie! By the way, welcome to the forum!
Her face and body shape look a bit "off" for a GSD to me, but it's a little hard to tell from those photos. How much does she weigh?
Do you have any photos taken at her eye level, but from further away?
Or any photos of her standing taken from the side, like this: