✔ 最佳答案
It sounds like your dog has a very submissive nature and possibly gets a bit over anxious when she can`t quite grasp what you are trying to teach her.
She also possibly "senses" your frustration ( even if you don`t think you are showing it) her for not understanding what you are trying to convey to her and this along with her submissive nature is why she acts as she does.
Dogs can be really astute at picking up on an owners body language and demeanour even if its very slight and you are unaware that you are displaying it.
My dog can sense my moods just by my general posture and this can be quite annoying at times!!
You do right to end the training sessions on a good note, but you cannot unfortunately change the way your dog behaves as its her genetic nature to act like she does.
Lots and lots of OTT praise when she does things correctly may help though.
Also, not ALL dogs take to training easily and your dog is still very young and her confidence could increase dramatically as she matures.
Hope this helps a bit.
參考: Gsd owner for 53 years. (uk)