Yeah it’s super easy (autistic or not) to think you’re being very clear when you have the full idea in your head, but you’re actually not. It’s like if you’re trying to describe a purple elephant and say “the thing that moves around and is purple and has a trunk”. Those words clearly describe a purple elephant if you already have the concept at the forefront of your mind, but for somebody without a purple elephant in mind, you could just as well be describing a purple car or a guy from the purple equivalent of the blue man group carrying around a big chest of clothes or a purple tree that can move around.