If you go through all the combinations of six items, there's 15, plus one more if you interact with other items in the house in a certain way. (I'm being vague to avoid spoilers, but you'll know if you've seen it.)
Sorry for the trouble! I've uploaded a walkthrough PDF that lists all the endings and their item pairings, which I hope will be of use. The only spoilers in it are the puzzle solutions and the titles of the endings.
