Hey Blondie- Congrats on the Bubs, I hope it all goes smoothly for you, and your wedding day is a hoot! Sadly there a so many people out there that ruin things, mine was my MOTHER!!!! I accidentally told them the day before our Ultrasound, (as I had a dream they found out from someone else) and I thought they would understand to wait until the next day before telling everyone. Later that day it was all over Facebook, and then everyone was posting on my wall. So I just gave in and had to write my Status as yes, we are, but early days yet. Imagine my surprise the next day when we had an Ultrasound that showed a Blighted Ovum, and we were told to wait 4 weeks to see if a Fetus develops. It didn't and we had a Miscarriage just before the next Ultrasound, but I have learned ONE valuable lesson!!! NEVER TELL ANYONE, UNDER NOOOOO CIRCUMSTANCES UNTIL 12 WEEKS!!!!!
It is sooooo hard as like you said, events that require Buffets and Alcohol will give it away anyways. But its harder to tell them bad news when it happens. Don't stress, I am sure everything will be fine, but it certainly isn't your fault, you had good reason to tell the Bridesmaids.

As for MrsHendo- Wowie, I can't believe ANYONES parents could begin to think it was their surprise to begin with. I understand they would want to surprise their friends with the announcement that they will be Grandparents, but Hooly Dooley! I would have *****SNAPPED*****