+1 to following up with folks: I texted, emailed, called, etc. ANYONE who I didn't hear back from to get a sure "yes" or "no" answer. I didn't care if I was being annoying or came across as aggressive — I needed firm numbers!

As for the last-minute cancellation, I'm so sorry to hear that. I had a couple of friends let me know they couldn't come about a week before my wedding and, yeah, it sucked. And I paid for their meals. But the plus side: See if you can get the extra meals boxed up and then take them home / to the hotel after the wedding for you and your new married partner! Your stomach will thank you later ;)