Sounds like you are doing very well with her and it seems like she is a good, typical GSD pup. Keep up the training and play sessions. Peronally I would not another dog until you have raised her for at least 1.5 years and only then add a male dog to avoid the two-female-problem.
Deja, GSD, sable WL, female, born 11 / 2013
Cam, Rough Collie, sable, male, born 8/2015