What is the ideal intake?

So im doing the Insanity program again. Last year i lost 1.5 stone with it. But my body shape didnt change which was quite disheartening. It didnt look like id lost any weight. I want to burn fat and really see a difference this time hopefully!

Im wondering if i wasnt eating correctly. Myfitnesspal calculated for me then that i should eat 1800 calories a day, and dont eat what i burn off.

This time Myfitnesspal calculated my calorie intake at 1490. I manage to get about 1200 in a day.
Is this really enough? As i have so many people telling me it is and then it isnt. I really want to get it right this time.:happy: