Shouting is a huge trigger for me, too.
I trigger immediately.
I do the fight, flight or freeze immediately.
Anyone shouting at me and showing aggression toward me has drawn a wild card, because I am as apt to react by standing up to them as I am to take flight. It scares me. It makes my adrenaline flow to just write this much.
I hope you've been able to calm yourself and can stay calm... and safe!

WC