what are ways to discipline myself into not eating?

My weight is like a yo-yo, sometimes it will be at 109 pounds and the next day 120 pounds. I hate it, I am also so short so even a little weight gain and it shows. I am starting to work out vigorously to lose the excess weight and feel comfortable with myself. With that in mind I want to lose about ten pounds this month and eventually get to 100 pounds. Can anyone please give me ideas or tips??  Motivate me!

To me a 100 pounds seems too light for a teenage girl and also the most you should lose in a month is 8 pounds since the healthy way to do it is by losing a maximum of 2 pounds a week. So if you do want to lose weight make sure you do it the right way. If your under 20 you should eat no less than 1500 calories a day. Also make sure you get a lot of fruits, vegetables, protein, dairy and healthy carbs in your diet. Make sure you also mix up your exercise routine so that your body wont adjust to the workout and burn less calories. Oh and drink lots of water since it will give you more endurance when working out and it helps fil your body up. Good Luck

thank you!