Lovely little story!
Interestingly (to me, anyway), I've got a good memory for text, but it doesn't often create mental constructs beyond text. No pictures, seldom sounds. On occasion, I've read fanfics where character dialogue is so spot-on that I "hear" the character voices (oddly, usually Japanese actors who — in my head — are suddenly fluent in English), but that takes some priming, like a recent watch of the source material — and it's usually in a pause from reading proper.
I'd wonder if this is related to two recently widely discussed psychological oddities: aphantasia (the inability to produce mental images of imagined objects), and a lack of internal monologue — except I can visualize objects and I most certainly have internal monologue. In my case, it's more likely related to the odd workarounds I constructed to read very quickly despite mild dyslexia.