I also agree that you are not getting enough calories. I know it sounds crazy, but you need to eat more to lose more in your case! A good starting place would be to cut down to say 1700 calories for a few weeks, then go down 100 calories every few weeks till your around 1300-1400. Another danger you face is a very very early plateau. With a plateau you need more 'ammo' in the way of cutting calories and stepping up the exercise. With only consuming 1000 calories, you've run out of ammo right there and then for the future.
You don't become overweight over night and you sure as hell don't get skinny overnight. It takes time, as frustrating as it is, you just have to be patient.
Next time you're in the supermarket, hold your hand 4 blocks of 250gr butter and remember that USED to be on your body...when you look at it like that, 1kg is a very good loss.
Also be aware of other positive changes you notice such as clearer skin, more energy, increased fitness. These are all wonderful changes that you should embrace, not just what pops up on the scale.
The following diet for 1 day would leave you feeling more full with more energy, more satisfied and will help you to lose weight much easier as you're putting wholesome, nutritious food into your body while still sticking to a low cal intake.
2 weet-bix with lite milk and 1/2-1tsp sugar
1 punnet strawberries
Ham/chicken/turkey (lean) and salad sandwhich with low fat cheese on wholemeal and seeds burgen bread. This bread is low cal, high fibre, high protien and many GOOD fats.
Low sugar low fat yoghurt (such as yoplait forme range) and a slim secrets bar (protein)
100-150gr grilled lean meat with 1 scoop mashed potato (you can add in 1/2-1tsp low fat butter) and lots of steamed veggies such as cauliflower, broccoli, choko, zucchini etc
WW fruit and jelly
Now that is only 1400 calories or so, so you could even add in a bit more food.
A cup of warm water with a slice of lemon in the morning will kickstart your metabolisim for the day and at night will curb cravings. Drink at least 2 litres of water a day and try not to eat after 8pm, or at least 2 hours before bed. Get at least 8 hours of sleep of a night and start to explore different exercises that you enjoy and will keep you motivated. Some suggestions are DVD's - there is a huge range available that is fun, gets you sweating and burning calories AND you can do it in the privacy of your own home! Gym classes are great such as step, body pump, body combat, pilates, yoga etc. Cardio at the gym such as treadmill, stepper, bike, x trainer. Incorportate some weights. Swimming, skipping, throwing a frisbee, doing a home circuit of calisthenics such as push ups, sit ups, mountain climbs, squats, lunges, star jumps, jogging on the spot etc. Wherever possible pump up your fave music that gets you going, makes it so much more fun!
Whatever you do, you have to enjoy it and have a bit of fun along the way or it's just too hard and it just won't work.