That's what I was going to say!
I also find that a fear aggressive dog is more sensitive to things like transitions and it's easier in the long run to keep them with you.
Is she mostly like this with dogs or people or both? I am weird in that I have some confidence with FA and people but am a basket case with FA and dogs! So I do understand that stinkin thinkin that we get in trying to help our dogs.
Really wasn't trying to speak for you
I remember the same feelings the OP described and trying to locate the right trainer. I've had fearful dogs before, but Woolf has put me through the wringer. Wading through the trainers, some who just promised more then they could deliver, others who just shouldn't have said they handle aggression issues was an experience in itself.
Well it's both. Initally it was mostly towards dogs she didn't know but it's also human & that's the one that really freaks me out. She hasn't bitten anyone but she sounds horrific.
Since I don't know your dog and only guessing here, don't take it for anything close to fact. Since the HA has started after you first realized the DA, I wonder if she isn't picking up on your emotions - the anxiousness, tension - and deciding she has to 'handle the monster' herself.
With Woolf, who has been HA sometimes from the beginning, the only time I could say he wouldn't react is if he was completely ignored by the person, otherwise it was all bets off and then I would separate and crate him. It has progressed to now initially he is leashed (issues of the opposite now, he gets to excited) until calm, then allowed to greet the person. I usually have to call him back to give the person a break from being shown the ball lol. The reactions I get now is when it is my fault. A person appears unexpectedly, surprises me then he will react. That is the next goal I have to work on - me staying calm when surprised <sigh>
Lot of text to explain what I meant by picking up on your emotions.