Meal plan - fill your stomach with 1/3rd food, 1/3rd water, and leave 1/3rd empty.
Eat 3 meals only per day.
Make your food - 1/3rd carbohydrates (bread, pasta, etc), 1/3rd protein (meat, lentils, eggs), 1/3rd vegetables (assorted).
Eat no more than one fruit per day.
NO SUGAR. Your only source of sugar should be that 1 fruit. Make it a small one. Don't care about fats & calories, unless it's too much, sugar is what matters.
Exercise 1 hour per day. Avoid treadmill, do more of cycling.
Exercise pattern - Warmups (not part of 1 hour), I would recommend walking and something for the upper torso, some stretches. Cycling - 8 minutes. Followed by - pushups (wall pushups since you're a girl), situps, woodchopper (google), leg crunches (google),
light weights (you don't want to be muscular now, do you?...), skipping, , NO STOMACH CRUNCHES WHATSOEVER, it doesn't make you lose weight, it's ONLY for abs. Then, I would recommend you go for a jog, in a natural surface, such as a mud track, a maximum of 10 minutes. Treadmill is evil. All exercises should be done in 2 sets, except jogging and cycling, which should be done once - pushups - situps - pushups - situps - woodchopper - leg crunches - ....etc. Do not do each more than 15 times, ie, 15 movements per set.
Inshallah, you will be of normal size in a few months.
{EDIT}
Come to think of it, end your exercise with another 5 minutes of exercising, no more. I would recommend you search on google for websites explaining all these exercises plus all the stretches you need to do afterwards, as you don't want to have any problems.