Thanks for the nice story note :-)
I think it's fair to say most of us have trouble with language pragmatics (use of language within a social context). However, that doesn't always manifest the same way for all people. I don't have trouble with literary metaphors (I find literary conventions fairly well-defined and easy to follow, way more-so than how people communicate in reality) but I'm perpetually stumped by the question "how are you." Being unable to cope with metaphor is true for some autists but is a faulty stereotype when employed across the board.
That said, a lot of the metaphors I use in my fiction are just how the images concretely come at me before I assign words to them. I see sadness as a fluid thing that smashes into someone and pins them, drowns them or washes them clean--quite literally that's the movie playing in my head. So I write down what I'm literally seeing. A breaker of sadness. It comes out as metaphor, but it was a bit more concrete in my imagination.
As yet another side note, I just finished doing a narrative analysis of autistic story-telling for a qualitative methods research class (did you know I've gone back to finish my systems science PhD?). The analysis showed no less rich or formal story-telling than the non-autistic narratives I compared it to. Hoping some day to have time to expand the analysis to a publishable size.