Hi Davis,
First of all you are not a hopeless case, I honestly feel that this is an issue of timing for you. The early days of CD are very hard and the easiest time to be tempted, the when you will be punished the most for leaving the program.
I was going to start this diet in February, but I had a lot of things coming up dinners and nights out etc and my CDC advised me to consider if the time was right for starting, and perhaps putting it off till I got past these events, that were coming up in quick succession, and that would be a better time to start and when I would have less temptations particularly in the early and hardest weeks.
Now I think that this was great advice, because I think I would have just yo-yo'd and got fed up with the fluctuations of the diet from dipping in and out of it.
I am not saying that you should do that but just putting it out there as an option, to consider starting when you have 3 or 4 weeks where you can avoid temptations and get fully established in ketosis before having to put temptation in your way.
I think if you stay on the diet this week and go to the wedding and eat normally you will be back to the same position as you are in now, and you will get seriously fed up with the diet. Unless you can go to the wedding and enjoy it eating only protein and staying off the alcohol, i think it might be worth considering putting off getting back to SS until after the wedding.
Alot of people who do take planned weekends off are doing it a few weeks into the diet, and some are having + or STS results those weeks, it really depends how off program you go as well and how long you have to weigh in when you get back to SS.
I hope you dont think I am being negative, I think you have to be realistic about the plan it works but not the way you would conventionally expect and it truely needs us to be committed fully to it to see good consistent weight loss
Best of luck with whatever you decide.