Is the reception traditional? With a sit down meal? Or is it buffet? Or is it much more casual?
I'm thinking of it as I would a restaurant out with friends.
I might have a meal somewhat before or at least make sure I wouldn't be starving by the time the reception starts.
I'd skip the appetizers, and then keep portion sizes in mind for the entree. The palm of the hand for the protein, a fist for rice or pasta. If it's huge, then I'd even cut everything in half before starting.
Make use of the dance floor and go to other people's tables to chat so that you aren't sitting at your plate the whole time.
And, of course, go easy on the drinks.
As far as counting points, do the best you can with what you know is on your plate, and then maybe add a point or two for "unseen oils and butters", as they can sneak into any meal.
You'll be fine! Enjoy the celebration!
