I'm looking for a different trainer who is more custom to GSDs.
My last trainer kept telling me to spray her with lemon juice which I found cruel. She also would hang her by the prong collar while she cried and told me it was just "her acting and trying to manipulate me."
While I love Cesar Millan she was trying to copy him in all her training no matter the breed or the problem.
Cesar Milan doesn't train dogs.
You really do need a new trainer though, negative stuff like hanging and spraying with lemon are about 1/10th as affective as positive reinforcement, if that.
7 month olds can be a problem. I know, we have one. They like to test all the boundaries both newly discovered and all the things they already learned just to see if you really mean it.
As I'm typing this, I can hear my wife saying NO!, release, Ow, etc in the other room, haha.
We're lucky I guess, we go to a GSD trainer and right now ours is in puppy or first level obedience.
Zazzle, in purple collar.
It seems like your girl really needs to burn off some steam at dog social get togethers (lots of socializing) or ball chasing or the like too.
Hey, good luck. These dogs invariably turn out to be the best there are after they mature.