I made the mistake of sending my first GSD, Kaiya, away for 4 week boarded training. She is also a reactive dog, and I felt much the same way you are feeling now, that I didn't have enough experience to train her the way she needed. I would never do it again.
When I picked her up, the spark was gone in her eyes. Her coat was dull and dirty looking, her gums were bleeding and she had green gook all over her teeth. I could tell they didn't feed the food I sent with her because she was covered in large patches of hotspots. I'd explained to the trainer that she was allergic to grains and had to be kept on what I sent her. It was obvious they fed her whatever was on hand.
Her reactiveness did not change at all, and even when I arrived, the trainer had a hard time getting her into a sit and down. She tried to explain it away by saying it was because the dog was happy to see me and needed time to settle.
Reactive behavior and training is not really something that someone else can do for you, despite what many trainers will have you believe. Dogs feed off of us, and unless you yourself learn how to work through your strengths and weaknesses in training, it's not going to do any good to send them off to someone else. They could perform perfect obedience for them, and come home to the same behavior with you.
It takes time to build a good working relationship with your dog, learn to read them, and understand their behaviors. I can now with Kaiya, at almost 3 yrs old, walk down the street without any outbursts on leash because of how much training we've done together. But my husband? If he tries to walk her, he will get the same behavior I used to get. Because she is bonded and trained to me and what I expect. With reactive dogs, it can seem like a slow, forever process. But the more you work with her, the more you will learn, and the better off you BOTH will be because of it. Find a trainer that can work with you and your dog. Good Luck!