I'd say 2-3 times a year for fast food is more than acceptable ;) We don't have White Castle here, but I know the more you eat well, the more fast food typically starts tasting like trash, so I'm guessing their food must be pretty tasty to retain appeal.
It sounds like you have a great, balanced diet. And dark chocolate is considered by some a superfood :D and not a day goes by when I don't remind myself of that :))