Yep she sounds like a Labrador puppy! They are usually pretty energetic as puppies, and some have a high prey-drive like my yellow girl, Rita (she is pictured below in my signature.)
I use the Gentle Leader head collar on Rita, and it works very well. It is designed to work the same way as a horse halter, if you lead the head, the body will follow. When attached to a leash, the dog should always be walking at heel, preferably on your left side. There should be some slack in the leash, and when you are correcting her you should pull in the slack in the leash.
Sorry, I don't know too much about the Halti, but you said you are in obedience classes? Ask your instructor for some pointers, they will point you in the right direction!

Good luck with her!