Hi Bluegem,
Weddings are probably one of the toughest environments to be in booze-free, especially at the beginning. I can understand that you can't get out of it, and you probably don't want to get out of it. Since I've been sober I've been to a few events where I've been the only person not drinking, and like you, I was always the partier and was expecting everyone to find me not drinking a very bizarre thing indeed. As it happens, most people really don't care. I've been sober four months and have been in drinking situations sober countless times and only very, very rarely has someone brought this up and made me feel uncomfortable.
Don't worry about what other people think about your sobriety. It's none of their business, and it has no impact on you so long as you don't let it. Remember that any urges you have to drink are just that - urges - they are not commands and you do not have to act upon them. Focus on what you're really there for... to celebrate your friend's marriage.
Hope you enjoy the day.