I wouldn't medicate, it's a band aid not a solution.
Every dog has a tell. You just have to learn it. Work on her in a controlled environment to start. Once she has that down, then start working her in areas of very low traffic. Work your way up.
If you have to ask what is aggression and what isn't, then you do not know your dogs body language as well as you think you do.
"i can explain it to you, but i can't understand it for you."