I'm 5'5, female, and 14yrs old. When I eat alot of junk food for awhile, I weigh about 120lbs. When I'm on strict diet and exercize, I get down to about 113lbs, and look and feel much better about myself. All of the websites I've been on tell me that 127-132lbs would be a good weight for me, but I just cant see that happening. Can someone please tell me what I need to weigh to be healthy?
All the websites, at most, use BMI which do not take into account bone structure and muscle mass so the weight they state are not accurate and should be used as a guideline. However, at 113, you seem a bit light for your height, 120 all the way up to the suggested weight that the websites told you, 132, seem like a healthy weight for you. As most females are, you're probably just more focused on getting the socially accepted, attractive flat stomach, thigh gap, completely flab-less etc, and therefore you felt the need to lose weight at 120. 120 is perfectly fine at your height though there is nothing wrong with eating healthy and exercising. Just focus on eating healthy (which also means a good amount for you), you don't need to lose weight AT ALL especially with the weight you lost already, and you will be fine.
I think you are perfectly healthy the way you are, you could go to a doctor and have blood tests to make sure you aren't lacking in any nutrients ect, and have your fat percentage measured if you want. I think bmi scales are often not very accurate because they don't usually consider age, and if someone has a lot of muscle they can be considered overweight while having less fat than someone deemed underweight and also, different people have different bone structure so don't be worrying about that too much. Keep eating healthily and exercising and you will be fine.