She sounds like she's doing very well in her class!
Are you sure you had the Easy Walk, or that you had it on correctly? It is physically impossible for a dog to pull on those harnesses -- they simply get turned around to face you. I just can't imagine how she could pull on one of these as there's no point of resistance. I have seen Tara and Lisa use these in their training classes on huge dogs that pull and they just physically cannot do it with the lead attaching to a ring on their chest. Just wondering if you had it fitted correctly by a trainer (maybe have your class trainer check it?) or maybe are using something with a similar name?
But again: you are really talking about a very young dog that is still a puppy and only just learning. I think once you start working on this in your class setting, you will have an easier time training her to walk on a loose lead.
Of the two below, I prefer the Sense-ible mainly because the lead doesn't swing and the clasp doesn't bang on the dog's chest. Also the bottom clasp is designed not to end up right in the dog's armpit. Other than that they are very similar.
Easy Walk:
Sense-ible: