Have i over eaten today?.....?

Assuming that you ate this in the order that you wrote it, here's what you did wrong: You ate too little during the day, which caused you to eat too much of the wrong stuff that night. Nothing that you got from McDonald's is healthy, and whether it's healthy or not is all you should be concerned about--not calories. Eat more healthy food for breakfast and lunch without worrying about calories, sugar or fat, and you won't eat something harmful like McFlurries and cookies later. That's the trick--eat a lot early in the day instead of letting yourself be hungry all day (when you're busy and have the willpower to ignore your hunger) and then trying and failing to find the willpower to avoid bad foods in the evening.

no, you have not over eaten. you are 14 years old you need to eat more so you can develop properly and your weight fluctuates multiple times throughout the day so it would be hard to even tell.