Confused about Caloric Intake, help!

I went here to get my daily number http://www.phord.com/cc/

which was extremely helpful.

I'm taking in 2000 calories per day, and I am 300lbs.

Question is, how will I know when to lower it, and, when I reach my goal weight, will I always have to maintain it at a low caloric intake?

I don't have any scales, and I only get weighed at the doctor's every 3 months. I cannot afford to really buy any scales at this time.

I greatly appreciate any suggestions! I'm new at this and I do apologize for my dieting ignorance :)

This site will help you determine your daily caloric intake.  It will ask you a set of questions, that most doctors and nutritionists would ask, to help determine what you burn.  You can also determine what you want to lose in terms of weight and it will help you determine how many calories to eat daily to lose a specific amount of weight per week.

I would see if there is some way you can weigh in more frequently than every 3 months.  Many times a doctor will allow you to come in and weigh yourself weekly without an appointment to help yourself keep track.  Or there are other places to find a scale to try and weigh yourself more frequently.

If you keep track of your weight loss in this site, it will adjust your daily caloric needs for you.