At 9 months she could also be going thru another fear period. Even tho you have socialized her, gone to classes, I would CONTINUE to do so. One or two sets of classes especially when they are young, just isn't enough, it's an ongoing thing.
If she's bored, up the exercise, take her hiking, run her, a tired dog is a good dog
Does she have any 'doggie' friends? If so, get together with them and let her play, another good workout.
As for protection, well the majority of dogs are going to protect themselves before they would their owners. It's called "self preservation"
No one should expect their gsd to protect them unless of course they have trained for it, or purchased an already trained dog. The majority of them don't grow up "protecting" their owners. Usually, their looks and a bark is a good enough deterrent.
I don't know why this would be a hurtful situation within your relationship with your boyfriend, these dogs don't train themselves and he is just going to have to except that.
With that said, my suggestion, forget the protective thing, get back into an obedience class , socialize MORE, dont baby her, but don't correct her for being "afraid", it's not her fault. Up the exercise, and make a plan for a daily routine.
I guess you have to think of it this way, would you rather have a dog that is more social or one who is going to fly off the handle and bite 'whomever' which would leave you open to a lawsuit? That's why I would forget the protection thing, and go with the obedience/socializing to build her confidence more.