Did I eat too much?

For the whole day, that is certainly not enough... Even if you're on a low-calorie diet, you need at least 1000 calories for your body to have enough energy to maintain its many functions. I know that consuming low numbers of calories may seem like a good idea, but it generally backfires because not eating enough signals to a hormone that produces more fat to keep you alive (even though you aren't ACTUALLY dying, your body thinks you are). This will make you GAIN weight, the counter-effect of what you're likely trying to do.