I would agree with everything Erica M. said above and add that it's going to take a lot of time, patience, and consistence. My dog was extremely reactive (and borderline aggressive) towards other dogs when I got her, and it took almost a year for her to be able to calmly pass any other dog. With your pup it may not take as long because she is younger and probably doesn't have a bad history with other dogs. Another thing I'd recommend is checking out the dog trainer Zak George's YouTube videos about leash reactivity. I've found his stuff very helpful.