I just made these for a dinner party, and had a similar problem to Jessica. Mine did still fit on the mugs I have, but were much larger than yours. It’s a great recipe and an amazing ideas, nothing but compliments, I used red and green M&Ms to decorate, which went down well with the younger guests. Perhaps it is a difference in paper size? I used A4 as opposed to US Letter, so perhaps that affected the size they came out.
Thanks for the extra notes, too! They really helped :)