Wow, she's got so big! And beautiful!

About the cowering. When she acts like that, don't TALK, TOUCH or LOOK at her. Any attention you give her is rewarding her behaviour (you see it as comfort). Would the instructor/teacher of the class allow you to leave the room? I bet if you let her in for a class and left the room, she would come out of her shell more.

Or, trying running around with her, all over the room. Run up to other puppies (not so crazily that you scare them, though) and shower them with love and run away again, calling Remy. Bring a toy, shove it in her face.. be playful with her. Don't be boring. It'll help her become more outgoing.