You can just find all passwords in the game, i believe they're not THAT well hidden. If there's something you haven't seen, maybe you need to make different choices with familiar passwords? (also, if any help, i found my notes about passwords and apparently there's 12 working passwords.)
I also have kind of a bad memory, but thankfully to their relevance to the plot, i have remembered all passwords (actually working ones and those that just appeared in the story) since autumn and never forgot them. Maybe that's because i have wrote a guide for my future self (didn't really used it while playing though). Buut i don't want to write them down here, as it is severe spoilers and i don't want anybody unfamiliar with them to see them. Anyway, good luck with recalling/rediscovering passwords. Maybe you'll write them down, too.