german shepherd aggression

hello everyone
my german shepher is 3 and a ahlf years old i made the mistake of not socializing her with people or other dogs because of what happenedwith my old german shepherd when i was a kid and now i am ahving a hg problem with my new german shepherd and i don't want her to be the same way as my old one was she lunges at people if they get to close to me when i walk her and when she sees another dog her hair is up and she is growling and pulling wanting to go after it but only some dogs she does this to others she acts afraid of them she has her hair up but the pulls back and i have to yank n her to gether to come, and some dogs on a leash or are tied up in there back yards if they bark she trys to bolt and dogs off leash she'll want to fight or try and run depends i know it's my fault for not socializing her but i kinda trained her to protect me when she was 6 months old because i was being stalked by a guy and no one did anyhting about it so i use her for protection i basically screwed my dog up i think and i want to fix it before some horrible happens i got the prong collar and it help a little bit and i try and make her sit and stay when a dog is coming and wait until the dog passes by us she sometimes dog but then if the are like right in front of us to pass by she lungges and i hold her back am i doing the right thing by making her sit ans stay or should i do more or something se i use to cross the street but i'm fed up with having to have to cross the street to avoid a dog?