I've always heard that the minimum should be 1200 calories or you go into starvation mode. In fact that could be why you're not seeing your weight budge. The body is good at slowing down the metabolism if it detects a danger of starvation. That's why just cutting calories is rarely a good long term weight loss solution. Your body adjusts to a certain number of calories so you have to cut them more... then it adjusts again so you try cutting more calories... and so on all the way to a severe eating disorder. You'll probably find that increasing your food will actually help you lose weight quicker. Give it a try. What do you have to lose but a week of your time? And potentially you'll find a much healthier way to lose weight which allows you to eat more than before.
Have you plugged your height and weight into Calorie King
? Many people here use that site to count their calories. It should tell you how many calories per day you should be eating.
And if you are still in doubt, go and see a nutritionist. They're far more knowledgeable about these things than we are! And your long term eating habits can have far too many health implications not to take them very, very seriously.