The truth is that there’s actually nothing particularly weird about being able to read some kanji but not be able to write them…
You actually get close to my point here:
> Admittedly, I've never heard of someone forgetting how to write a letter from the Latin alphabet.
Yes! But have you ever heard of someone forgetting how to spell certain words in a language that uses the Latin alphabet (e.g., English)? I can use myself as an example here: while writing this comment, I forgot how to spell “peeve” in “pet peeve” (I thought it had an ‘a’ in it) and I also forgot how to spell “unnecessarily” (I thought it had one n and two c’s).
The western equivalent of being able to read some kanji but not write them is simply called bad speling. No need to mystify kanji in particular.
But there's nothing crazy about that, like you said it's similar to spelling (not entirely, as I can spell things fine if I have a phonetic keyboard that "writes" for me).
Writing vs reading to me, is more about the type of memory.
Recognition vs recall.
As many have said in this thread, most doctors will tell you to go away or give you Welbutrin (which works poorly, if at all). I feel for your struggle.