It doesn't seem so bad. Mine isn't even on any lists, nor has it ever been classified, that I know of. Same as you, only two people know of mine and they aren't phased by it. It's very very specific and literally the only thing that gets me off, which is kind of sad because I have to pretend I'm having a good time with my partner when really, I'm thinking of something else. You are brave. Much braver than myself. I, too, get hella nervous if I see anything that reminds me of it. No. I stop in my tracks. I have to run and isolate myself. I try to get away without anyone noticing. It's a bonefide trigger because I freak the hell out anytime it happens. I've accepted it as part of who I am but it's still very very powerful.

Not sure where they come from. Some can be pinpointed to certain events which happened early on in life but some have no rhyme or reason. I say as long as it doesn't a) cause harm to anyone, b) impose on anyone's will and c) break any laws, then you're in the clear.