I agree totally with what Carrie has said. Please do not give up on your dog. Work with her on a daily basis, spend quality time with her, and see your vet for more help. I truly believe this is a genetic problem because of all the goldens I have heard of with nervous tendencies.
Unfortunately my family had a similar experience with a very nervous golden retriever. She was frightened of strangers, unusually protective like your dog, and incredibly afraid of loud noises.
We eventually got her socialized to people and handled the loud noise problem with medication. Just when we thought we had everything under control, she died in a tragic accident while we were on vacation. The dogsitter left her outside during the 4th of July and she had a nervous breakdown because of the fireworks, ran away, and choked herself to death with her leash. It was incredibly horrible because we had just conquered the majority of her behaviors.
I promise you, with the right help and persistence you can help your dog. Please learn from what happened to my dog and DON'T GIVE UP. WORK WITH HER EVERY DAY! Honestly she may need medication but that is no substitute for the love and training you can give.
Good luck and best wishes.