I know you say you're full, but (hopefully not offending here), you must have eaten a lot more to have reached your BMI. I've been there...done that.
If you can accept that it is going to take a fair bit of time to reach your target, I find it's easier then to stick to a healthy 1200 calories a day, accepting that the changes will be gradual.
Maybe alternate days of 1000 and 1200, on the second day having something you would really like, like a glass of wine, or a small chocolate bar?
When I started dieting I dropped to 1500 calories and I wish I'd started higher. I would've still lost and once my weight loss slowed I ended up after a while with nowhere to drop down to.
My advice is find out what your maintenance calories are and drop somewhere between 1000 and 500 cals from that. That way you'll lose 1-2 pounds a week and once you slow down you can adjust your calorie level down.
It is also not really possible to get all the nutrients you need on less than 1200 calories. That's why VLCD's have added proteins and vitamins etc.
So speaking as a long term dieter my advice is slow and steady..it gives you more choice, more lovely food and retrains you to eat sensibly. It's also much easier to stick to and shouldn't hammer your metabolism so much.
Hi Stef
This calculator might help..
Calorie Calculator
I used the info in your sidebar and guessed your age at 25 - the result was 2523 calories to maintain your weight if you are lightly active. 2844 if you are moderately active. Drop 1000 of either of these and you can still eat quite a bit and lose 2 pounds a week. Anyway have a go with the calculator yourself (with the right info!).
I use calorie-counter.com to record my food and that has a calculator on it.