Not OP, but It doesn't matter to me what they are. It can be a call to discuss weekend plans, it can be an errand I have to run, it can even be an agreement with an friend to play a multiplayer game at X time. Something like a dentist appointment is the worst though.
I'm neurodivergent and not sure how much that matters to the phenomenon
I think it's general anxiety. I get butterflies in my stomach when I do anything off my routine. Even if it's just hanging with friends. What do I wear, how do I get there, will I know people, should I bring something?
Yeah, I keep seeing autism and ADHD memes, and keep thinking "I do that all the time". Should probably talk to someone about it who can give a proper diagnosis.
In the US some medical providers charge the cost of the visit without insurance if you’re late or don’t show, so a $20-30 appointment can potentially turn into one that costs hundreds. That alone makes me anxious about appointments, because I don’t know off the top of my head if any of my providers do that because I’m neurotically on time, lol.