Aside from what was already mentioned. GSD's tend to take a while to find their butts and can have a sway about them. My female was about a year to year and a half before she carried her butt well.
Misty- Samoyed Mix, Tannor- Golden Retriever CGC
Robyn- GSD CGC, TC, Midnite-GSD CGC,TC, Brennan-Golden Retriever CGC, Batman-Husky/Greyhound , Apollo-GSD