What is the correct weight for a 16 year old girl?

Range. According to the us cdc, the average weight of a 16 year old female is 118 lbs with "normal" ranging from 94.5-172 lbs. Ideal body weight depends on your height though, so please discuss this issue with your primary doctor at your next visit. http://www.cdc.gov/growthcharts/data/set1clinical/cj41l022.pdf.
Unanswerable. Unfortunately first you did not include your height. But, this would be better answered if you described your weight and then get specific questions about what you are worried about. The ideal weight is nearly meaningless in real life.