It isn't always about how much you eat as it is what you're eating.
500 calories of high fat, high cholestoral is not going to react with your body the same way 500 calories of high fiber, lean protin will.

Unfortunatly, the only sure healthy way to lose weight is eating good healthy food in reasonable portion sizes, and exercise. If anyone tries to tell you otherwise, they are selling something.

Also keep in mind that a good healty weight loss target is 1-2 lbs a week. 1 stone in 4 months is just under 1 lb a week. Its hard to tell from your post how active you have been in the process over those weeks, but so far its a decent start.

The hardest thing to keep in mind is that is doesn't go on quickly and it won't come off quickly. With perservence, it will.