I am too lazy to look it up, but someone said the only way to follow a diet effectively is to find new ways to eat that you enjoy more than the old ways. If you feel like you are missing out on chocolate cakes (and chocolate in general) there are solutions if you are willing to put in some work in the kitchen. (Important note, I started following low carb in January of this year and at that point I could not cook an omelette. These recipes are not too difficult to follow if you are cuisinely challenged like me).
This is an almond meal chocolate cake I made this afternoon.
View attachment 3764
Believe it or not it's very low carb, using Stevia instead of sugar, unsweetened cocoa and cream cheese icing.
http://low-carb-support.com/chocolate-cake-lowcarb-gluten-free/
I had a slice of that for dessert tonight, but for my main course I had... Pizza!
http://lowcarbdiets.about.com/od/breads/r/flaxpizza.htm
I used basil pesto, mozzarella and a slice of salami to top the base with. My blood sugars after dinner were 4.4, so I can vouch for the effectiveness of this meal.
What I am trying to say in a roundabout way is that you should look for ways of adapting your favourite foods, rather than resisting and giving in occasionally. I have come to prefer Stevia to sugar, and I find it laughable that I used to look forward to Domino's pizzas.
In relation to your question (which is far from stupid, as is any question aimed at improving your health), one slip is unlikely to ruin things, in the same way that one low carb meal would not interfere with a high carb diet. It sounds like you are taking the right measures, it just needs a bit of fine tuning. Think of it as adjusting the saddle height rather than replacing the bike