I don't think you dog's behavior is about a fear stage from what you are describing at 8 months. It seems to me that your dog is acting up when she sees other dogs. She wants to play, chase, etc. That is very common with adolscent dogs. But unfortunately, it doesn't go away by itself. It takes work and training. Talk with your trainer about your concerns and that your dog doesn't want the treat when she sees another dog and that you are afraid. In order to help you and your dog, your trainer needs to know how you honestly feel.
Sting Chance von Gaard AKC GSD 2/8/2006