I agree...planning definitely eliminates a lot of the guilt.
Also, and I hope this doesn't sound weird, but I would recommend weight watchers. I do weight watchers and it eliminates ALL guilt because you know exactly what you are eating every week. For example, everything you eat has a point value, and you get a certain number of base points per day. My value is 29, so I eat 29 points of food per day. Then on top of that you get 35 extra points a week to spend however you like. So this pretty much eliminates all guilt, because I can eat a HUGE FATTENING meal one day a week, and use 20 of my extra points. Weight watchers teaches you balance in your everyday diet, as well as your weekly diet. It also teaches you portion sizing.
It kinda sounds like you're not even eating that much. Weight watchers will ensure that you can eat the foods you like without going over what you should be eating all day. For example, I could eat a piece of pizza worth 8 points, and still have 21 left for the day to spend however I like.
It's just a suggestion. I suggest it because I used to try to just eat healthy, with no laid out plan, and I found myself ALWAYS feeling guilt over even the tiniest bit of "unhealthy" food, like butter or chocolate or ice cream. With weight watchers you can eat that stuff as long as you are balancing out for each day.
Good luck! and stop feeling guilty!
It's okay! It won't ruin your success this far...just realize that it was a splurge and your lifestyle is changing for the better!