When we were doing zoom sessions, my T was two/three minutes late. It never bothered me because he always made up the time at the end.
I did feel what you’re feeling though, especially if he wasn’t online in those tow/three minutes. What if something happened to him? What if he forgot? What if he got his days mixed up? Should I call him? Should I give it another two minutes? It definitely created a vortex of anxiety.
I would definitely bring up how it’s making me feel. I’m sorry she was so dismissive of your feelings—I think I would have an issue with “you’re the only client bothered by it in the 30 years that I’ve been practicing.” It sounds like she was being defensive, which isn’t fair on you. She should be curious about the bigger picture.