How to change my diet to lose weight if I have been eating less than 1000 calories a day already
Based on what you are telling us, your body mass index (BMI) is 22, which means you are no where near being overweight.However, if you reduced your weight to 47 Kg, you would be close to being underweight, and, if you reduced it to 42 Kg, you would be underweight. There is not enough clinical data out there that suggests that Asians should have a lower BMI. Do not believe in that junk science. The Asian race is not even a real biological construct.
Even if you were overweight, I would tell you the same advice. Keep your caloric count at 2000 and make sure you eat a balanced diet. This is especially important for you because your brain and nervous system are still developing as an adolescent, which means you need a certain amount of fat. In fact your brain is going through a lot of rewiring now, and it needs a certain amount of fat to go through this.
Also, the more you starve yourself, the more your body will hang on to your body fat because it thinks it is in a state of famine right now. Our bodies were selected through evolution to decrease our metabolism, when our caloric intake goes down. Starving yourself is not only unhealthy; it is counter-productive, if you want to lose weight, not that you need to. Oh, yes, and skipping breakfast is not a good idea at all.
Try doing some moderate exercises, instead, if you are looking to improve your body shape. It improves your fitness, increases your energy, and makes you feel better, but that also requires you to increase your daily caloric intake.