Like Barb said, it might be a good idea to see what your calorie intake is for a day or two.
www.fitday.com is an excellent resource for watching your intake. I used it for a while just to watch my fat vs. carb vs. protein intake. I realized I was consuming way too many fats and not enough fiber. Again, you shouldn't have to watch your calories long term, but this is a good tool to help you stay on track sometimes.