Oh boy, sounds like Jack to a "T" when he was a pup .

The good news, she's young! I didn't start working with Jack and this problem until he was a little older, so it took much longer to correct.

I would enroll her into a puppy course NOW. Or when she's had all of her shots. The sooner the better, she will be able to interact with other dogs and learn the essentials. She only reacted the way she did because she doesn't know any better at this point.

I'm kind of busy at the moment so I can't go into great detail, and I'm sure others will chime in, but I'd work on desensitizing (working away from a distance and praise her when she's not focused on the other dog/distraction), or a watch me command.

But I really do think that some sort of puppy class would be the best thing for you to do at this point in time.