I knew I’d been screwing up my use of apostrophes.

Get this straight once and for all: when the “s” is added to a word simply to make it a plural, no apostrophe is used (except in expressions where letters or numerals are treated like words, like “mind your P’s and Q’s” and “learn your ABC’s”).

Right. Can I not be arsed to go back through all my posts.

This is a great page of Common Errors in English for the solecists among us.