It's on the "fix-it" list.

What I see the OP describing is any change in the environment, and the dog having a fearful/aggressive reaction to the change. The change can be from the dog moving through the environment itself, or others moving in the environment. I would definitely not correct (ie. punish) for this reaction, but I would work to help the dog learn new behaviours to deal with the feeling of threat that she feels when there is a change.

Resource guarding could be considered a symptom of anxiety - ie. something I consider life-sustaining is going to be taken away from me and my existence is threatened. If you interpret your dog's signals as expressions of anxiety, how would that affect your thinking processes about how to help your dog adjust?

It sounds like you can quite accurately predict when your dog is going to feel anxious, so you might use those instances as training trials to teach your dog to calm herself when she is exposed to 'threats'? I recommend taking a look at Grisha Stewart's BAT method and see if you can set up conditions to teach your dog new habits of responding to changes in the environment (because these new habits also accomplish what the current unacceptable habits do - relieve from proximity to the perceived threat.

I agree with other posters comments about the difference between corrections and providing appropriate guidance to our dogs. Sometimes it is difficult to discern what course to take, but any course that builds trust and confidence in your dog is going to be more effective over the long term than risking inflicting pain that is confusing, or attributed (by the dog) to the wrong source.

* to qualify the above, I am an inexperienced handler being trained to handle a reactive, confident, fearful/aggressive 2 year old shepherd x (in large part by said dog).

well I wasn't on to anything by giving her extra attention. And Jenny is right, absolutely any change in her environment sends her into a tail spin. I can only guess what life must have been like for her before me to make one so unreasonably afraid. Or maybe she is the result of very bad breeding, I just have no idea. Things are a little better, when she begins the resource guarding over me, I just get up and walk away so that she no longer has the resource to guard. When we come inside, I snap a leash on her so she can't start it when we walk in. I would say the growling and grumblng is about 40% better. she still does it if I walk in a room where she and the other dogs are laying. After sitting and thinking, I think the best thing is to just make it counterproductive for her by just walking away. Her other issues regarding fear just took some time or were easily eliminated. Company is a rare thing here, and if there is company she just goes to her place and hides, she no longer feels like she has to defend herself. Egads what a challenge this dog has been. She used to be so fearful that she would hurt herself trying to get away. She would slam her body against doors trying to get inside. I have seen her do it because a car pulled up, or because there was something new on the porch that wasn't there yesterday. She doesn't do that anymore, she def looks to me to just tell her it's ok, that new chair won't get you. She was so crazy I thought for awhile it would be a mercy to put her down. We'v really come a long way.