First...congratulations! ...and I hope you're not stressing too much!
Honestly when the day comes, you won't be thinking about food much at all, and you probably won't eat much of it! I was so filled with excitement that I hardly touched much. I had (now, mind you this was 3+ years ago pre-Atkins) my traditional bite of cake from my groom but never did eat anymore.
I wouldn't worry about your wedding day, and being overly mindful of staying on plan. What I would worry about is making sure you eat leading up to the ceremony, and like pp said, not too much sugar or you may endup not feeling well for later...if ya know what I mean!
Then when the day has passed, get right back on track. Don't use your honeymoon or the "wedding day is done" as an excuse to go crazy.
Good luck!
Amy