I've been in that same situation and this is what I did..
You need to work out at least an hour a day. Do something that makes you sweat. Alot.
Make sure your burning more calories than you consume. That's is how you lose weight.
Drink LOTS of water. 64 oz of water a day.
You need to trick your metabolism, so it doesn't slow down. Do this by eating 200 calories one day, 800 the next day, 400 the next and so on. If you just eat 500 calories everyday you metabolism will slow down and you won't lose weight as fast.
also, spread your calories throughout the day. Eating 5 100 calorie meals is better than eating one meal consisting of 500 calories. By doing this your metabolism will never have the chance to slow down. ( This will really work if your drinking water between the 100 calorie meals)
Weigh yourself in the morning before you eat and after you've gone to the bathroom, if you weigh yourself after you've ate(or at night) you might get frustrated and eat.
If you do this I promise you will lose weight in 1 month! I have to lose 15 pounds in the month too, so your not doing this alone. I've already lost 65 lbs in the past 2 years but I really need to lose the rest before I see my family for the first time in 5 years this Christmas. You can do this if I can.
Hope this helps