So your one of those all or nothing kind of girls. Well, guess what...your not the only one.
I am of the same mind. It's difficult to overcome that need for perfection or disaster and nothing in between. I don't win all the time. When I am trying to diet or change my eating habits, I often fall off the wagon by having something like candy or movie popcorn or what not and than I figure I might as well throw in the towel and pig out for another day. And I do mean pig out!!! When I do follow the plan I become obsessive and drive everyone around me crazy. We are not the only ones.
My friend quit smoking at the same time I did and she can have one or two when she goes out on the town and it doesn't make her start smoking. I know that I can never indulge that habit even one time because I will buy a pack the next day and the rest is all to heck. The kind of people that can do what my friend does don't understand the way we think or react.
I have already thought about the fact that after I get closer to my goal I will need to re-design this plan a bit to allow myself to have that 1 day or 1 meal or something like that a week where I can say, "if it's there and I want it...I am eating it" and it won't be cheating. If I plan it that way I hope that it will allow me to say "that was the plan and now It's back to normal until next time". I may even have to schedule these things if that makes sense.
I hope this helps and that you stay here at the site because I am glad to know that you are there struggling along with me to fight that need for perfectionsim.