Unfortunately some people just do not know how to respond...who knows why? I had the same problems with my fiances family. We didn't get RSVP cards back from them, but my fiance told me not to worry because "they are coming. Everyone in his family shows up for an event." Plus, he told me that the whole family would want prime rib (which was the most expensive item). I told him that's great they all will show up, but get on the phone with them ASAP because I'm not going to just add 30 extra people based on that answer. So, he ended up calling and it's a good thing because not all of them wanted prime rib and not all of them could attend.
The best thing to do is get on the phone with people. My friend had something happen with her invitations. She mailed them from her house, only to realize that their mailman had just been busted for throwing all the mail into a nearby pond - strange, but who knows? Maybe your invitations got lost in the mail somewhere.
I would call your caterer and explain the situation. Ask her if it would be possible to meet one week from tomorrow. This way you will have time to get an accurate guest count to her.
As for the people who have taken it upon themselves to invite extra's that is going to mean more awkward phone calls.
I know that it's horrible and not an easy thing to do, but take comfort in the fact that the people who care will truly make the effort to be there...you don't need a whole lot of people to celebrate a wedding; just people who love you. That's all that matters. Try to relax...grab a glass of wine and start making phone calls.
