Hi,
Keep that chin up, you will be fine by your Wednesday WI. Although you might not have lost as much as you do normally, I doubt if you will have put on anything.
I did the same last week in the form of two glasses of white wine. I did come out of ketosis for about 12 hours, but appreciate that alcohol is full of sugar and it was bound to have an effect. Therefore, I avoided the scales like the plague, drank as much as I could, and said a prayer before getting on the scales. The result was a 2lb loss, which was probably more than I deserved but the night out was well worth it as I was meeting Ladybird who sometimes posts on here and she is a lovely girl.
What I'm saying is you have 3 days to go, don't weigh, drink 6 litres a day and keep smiling you are doing great and you will most definately achieve what you set out to in the first place!
Take care x