Really wasn't hoping to hear this
I know, but it's good you asked, and it's good you're listening.
The fact is, temperament is genetic, so if your female is fear-aggressive, her pups probably will be too. In fact, there are an awful lot of fear-aggressive GSDs out there, it's why the breed has gotten a bad name. If you breed your bitch, you will be perpetuating this.
GSDs are not an endangered species, so it's not necessary to breed ALL of them. You breed only the best to the best. Not saying your female is not a wonderful, loving pet. She certainly deserves the best of what you have to give. Spay her, and let her be a wonderful pet.
If you think you want to get into breeding, there is a whole world of knowledge that you must have under your belt in order to do it right. This means lots of study and a mentor, going to shows, trials, and training. When you get to a point where you have a solid knowledge base (I'd say a minimum of five years of intense study), and you have a solid mentor, then you go about finding the right dogs for breeding.