As you no doubt are aware, eating too little actually hurts your ability to lose weight. In fact, if you slip into starvation mode, you will gain weight more quickly at 1000 calories a day than you ever could at 2000 calories a day.

Metabolic cycles can also have a tremendous effect on your weight loss, especially if your eating/excercise cycle causes "mini crashes" during the day. I'd advise adding 2 healthy low calorie snacks (maybe 2 small helpings of nuts or something) that would increase you to 1300 calories/day... then replacing 20 minutes of walking with some kind of cardio that is far more vigorous (which should easily counter the extra 100 calories - but those 2 snacks will help assure you're clear of starvation mode and perhaps help even out your metabolic cycle).

Try it for a couple of weeks, and see if it helps...

Also, if you have access to a gym of some kind (or at least a couple of weights), adding a couple of 30 minute resistance training circuits will help you develop more muscle mass, which significantly increases your metabolism... but that might be harder to accomplish for now, so one step at a time.

:)