mama-
With your current weight, I would start out at 2000 calories a day for the first couple of weeks, for two reasons:
~Most of us here in the calorie counting section are currently eating between 1200-1800 a day, but since you are currently eating a lot more than that-I think it might be best the first couple weeks to not drop it too drastically. You would probably feel too hungry.
~With your current weight, it is very possible for you to lose your first week or two at 2000 a day, since you are currently eating almost double that some days.
More advice:
~Try to space out your calories through the day. Don't eat only twice-having 800 in one sitting, and 1200 in another.
Try to eat, say 400 for breakfast, a 100 calorie snack, 500 for lunch, 700 for dinner, and another 300 for a larger snack. They don't have to be plit up exactly this way, but you see what I mean-eat smaller meals and snacks throughout the day. After a couple weeks of doing 2000 calories a day, and adjusting to counting calories, then drop yourself down to having 1800 calories per day.
~Try to get more bang for your buck. In the beginning when you drop your food intake down, you may feel hungry. The solution is to avoid eating too many foods that are "small" and not nutritious through the day. For instance, the little 100 calorie packs they have out now of little cookies and such, are fine now and then if you HAVE to have a treat and want to practice portion control and want something low calorie-but having them 2-3 times a week should be plenty. If you pour one of those packs out into your hand, there really isn't all that much there. If you are really hungry, with your tummy growling-it may taste good but it is going to be an unsatisfying snack. For 100 calories, you can have 2 cups of watermelon, or 2 cups of strawberries for 90 calories. It is not only much more nutritious, but you are getting more food for the calories.
~Get a small journal, or small pocket sized notebook to write your calories and what food you had in each day. (I am currently using a Hogwarts school journal from Harry Potter.

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~Get some exercise in each day. Actual exercise, not just your regular activities. Start small if you must with 15 minutes a day. Then if you are regularly doing that much a day for a couple weeks, move it up to 20 minutes for a while. The key is to get into the habit of exercise first, then after you are doing it-move up the time and intensity.
Good luck, and if you have any questions, feel free to ask.
Amy/Aphil