Oh, Brodys mom, just don't give up!!!!! There were days I'd honestly break down and cry after walks with Makena, she'd be so horrid -- nothing like a German Shepherd up on her back legs, barking/lunging/ growling/snapping, looking like any criminals worst nightmare, about to be taken down, me praying the leash wouldn't snap, trying to hold her back with all my might -- except the target of her rage might only be a chihuahua a block and a half away, or a beagle taking a nice walk with his family at the other end of the block, facing the other direction. And after the sight of another dog, and a horrid outburst, she'd stomp around for up to two days because of the horrid adrenaline rush. And of course it seemed these awful "sightings" always happened at the farthest points from home, and she'd spend the next 1/2 hour (or more) looking for more dogs to take on, looking for trouble, "just bring it on", and I just spent it praying we'd get home safely. And of coure, we'd walk in areas where there were almost no dogs - desolate areas. But one sighting was all it took. And I couldn't walk her with Alfie (who LOVES other dogs) cuz if she saw a dog with him, she'd immediately redirect onto him and then I'd have two GSs going at it, and she'd take him down, right there.
BUT - after loads and loads and loads of hard work, she's a different dog. She'll never be a dog park dog, but we all walk together all the time, she can pass other dogs, no big deal, no redirection, no fights, no barking, no lunging, nothing. It's a wonderful feeling. We just took a great beach walk last night, it was a beautiful night, lots of people out walking with their dogs at the beach (onleash), we passed so many, no big deal. Live and let live. We don't ever meet-n-greet (much to Alfie's dismay), but at least we can all have a relaxed walk together.
Don't give up on Brody, have faith in him, in yourself, and in your relationship. And keep asking questions. You'll find that 'thing' that helps with him, cuz not everything works with, or helps, every dog. But something will, or bits and pieces of this and that, will. And when you need moral support, we're here. I truly get it! Been there, done that - and still live it. I am ever-vigilant, and will always be. But things are so much better. Keep the faith!!