At 14 you should eat a well balanced diet that includes carbohydrates, fats and proteins.
As long as your diet includes a good protein source such as lean meats, including chicken, fish and any type of soy proteins will do just fine. You can also get protein in the form of dairy, such as skim milk and eggs.
Carbs no matter what you hear are not bad! There are bad carbs however! Refined sugars and corn syrup, will encourage fat storage and those are generally considered "bad" carbs. Try to stay from snack foods and soda pop. "Good" Carbs include whole wheat bread, oat meal and several types of fibrous fruit (granny smith apples, bananas, pears).
Lastly are your fats. You need to take in fat for several reasons. The bad news about fat is for every gram of fat there are 9 calories, the good news is you dont need much fat in your diet! You can get your fats from nuts, including peanut butter, avocados are a good source as well. Fats in things such as brownies and other snack food are not going to give you any benefits that the others i mentioned would.
Actually a great lunch for you would be a Peanut butter and jelly sandwich! As long as you are using whole wheat bread and the jelly is an "all fruit spread" (it taste's different, not bad, but different) then it really is a healthy meal. If you throw in some cashews, or an avocado, and some water you have a wonderful meal!
At 14 I would worry more about how healthy you feel as compared to how much you weigh. You aren't at a bad weight now so being healthy should be your #1 goal. You still have time to grow and develope so making sure you get the proper amount of things is the best way to go.
The best way to eat (it is still possible to eat too much of a good thing) is to eat until you dont feel hungry, not until you feel full. If you do this you might be hungry 2-4 hours later. WHICH IS GOOD! Our bodies were designed to eat every 2.5-3 hours, we dont often do that because we often just stuff our face 3 times a day and expect our bodies to handle the extra load we give it. But at each meal eat until you aren't hungry and have a snack in a few hours, then do the same, until your not hungry!