Gosh Carmen i am so very sorry that Luma is going through this. Luma must be out of her mind with fear and I feel so very bad that she is experiencing this. If she is like this when you are there can you imagine how she is when you are not. It seems to me that it would be pretty scary for her to be panicking and shaking the way you describe with no one to comfort her. One think that I would suggest is that maybe
if you put her in a cage during those three hours you are gone maybe it would help keep her calm. I would imagine like most dogs that suffer from anxiety that she is passing, hiding and trying to find some way to sooth herself. Please don't blame yourself, you are a wonderful mommy, you had no idea that she would react this way. You are doing everything you can to help calm her down and get her to adjusted so just keep it up and hope for the best.
I have hear of dogs being put on medications to help with anxiety. Not that that would be you first choice but if it were my pup and nothing is helping I would really consider it.