Before you leave for a walk trying doing a few minutes of training inside. Teach her some impulse control exercises such as letting her see, nibble, paw a treat in your hand until she finally backs away from it and at that second you say "good" "yes" or something like that and give her the treat. This will help you get her focus on you and/or the treats in your hand.
Then when you take her on the walk have the treats in the hand closest to her and try to get her nose to focus on the treats. She will probably snap and jump at the treats but don't give it to her and ignore this until she stops the unwanted behavior and then mark and treat (say yes, good, or click with a clicker at the VERY INSTANT she quits the bad behavior and calms down or backs off).
After this starts going smoothly you can make it a little harder and demand more than just a treat seeking missle dog. Do the same impulse control exercise before you leave for your walk, but don't give her the treat until she not only stops trying to solicite it from you, but she actually makes eye contact. This may be just a tiny split second and you have to be ready to mark and treat the eye contact. A second to late and you are reinforcing the bad, not the good. Then incorporate this into your walk. Eventually fade the treat.
Also, this is a puppy thing. She will definately grow out of it but this kind of thing will help you along the way.