If you have a dog with training issues (and there are a LOT of training issues here), getting a second dog is just about the worst idea ever. It will likely exacerbate any existing issues, and you may end up with TWO dogs with issues. It is not a substitute for training, and with two dogs you will have even less time to deal with the problems of the first one.
"She is only scared." Most dogs bite out of fear. Not saying that she'll ever bite anyone, but knowing that most aggression comes from fear is important. Start working with a trainer (one experienced with the breed) on her reactivity and obedience. This is something that really needs to be nipped in the bud before she matures.
Why does she need to be around other dogs?