Don't get disheartend, I think that she is just overwhelmed by so many at the one time.
Is there any dogs she does get on with. I have the same problem with Lottie but although she is terrfied she will bark and even try to nip the other dogs....we have been to a behaviourist who says try and distract her. well that did not work ,we took her to classes and she created blue murder barking at everyone. She would eventually calm down and could do all the commands , just as long as none of the others came near!!
We are trying clicker training and treating her for even the smallest amount of time she is calm and hoping this works. We have gotten her used to a few small dogs who she now quite enjoys meeting so we hope to improve on this.Like you we socialised her from day one , but she had a bad experience with a dog trying to pick her up..
Maybe if you could speak to the trainer and try to introduce one small dog to her or if they have a rebilation class where the have a non reactive dog that is very calm with other dogs that might help as there may be tto much going on the the trainning class for her. i.e the commands to be done and the meeting and greeting of other dogs.
You could try
ClickerSolutions Home for ideas.
Good luck.