Hey! don't worry! Even if you can't count the calories, you know what's got more calories and what's got fewer.
If you have a choice of plate sizes, choose a smaller one. Fill it mostly with vegetables and/or salad. Avoid the really sweet things and the things with lots of fats. Make sure you have lots of good food choices, and don't go back for more. You can get through it and still not blow your plan.
I just got through dealing with a Florida hurricane, and although I didn't stay with my food plan perfectly, I did OK with most things. I now just have to get strict again and back on plan, so that a couple of days of eating not the best way doesn't become a habit.