Hi!
How old is your pup? Did I overlook that in the post? LOL.
My Bella is 10mths old and is very much like you described. She growls and acts ferocious around other dogs but if they come near her, she cowers and screams!!! Really screams. It's fightening and frustrating. My SO hates walking her because everyone who has their dog out gets irritated because their pups/dogs are walking nice and just "smiling" at the other dogs, and Bella is acting like a maniac!
I know it's due to poor socialization (
) but it's too the point that it's hard to even attempt to begin socializing her because she goes nuts.
Sorry I don't offer any help... I can only relate.