Vet has ruled out all medical reasons for the way he acts. There's absolutely nothing wrong with him, he is as healthy as can be. :)
He is only aggressive when there are strangers around him. If it's people that he sees on a frequent basis, he is fine with them. He might bark when he hears the door bell but as soon as he sees it's them, his tail wags and he relaxes and he is fine.
We spoke with a trainer last week. It's a bit more pricey than what we wanted, but we would take him to her and she would work with him non-stop for about 2 weeks. We would come down there at the end of that two weeks, learn all the training and techniques they have taught him, and then bring him back home and it would be basically maintaining the training here at home. He would be "calm" for him, but would follow commands better.
She also said that German Shepards have a VERY high energy level and that if that energy is NOT worn off, it will cause things like separation anxiety - it will cause him to be destructive etc. She said his mind is too busy for him, and that exercising him more frequently will take care of that. However, in order to walk him appropriately, we have to get the training taken care of - because at 18 weeks pregnant, I'm not going to walk a dog that walks me. lol