If I am about 5'7 to 5'8 and I weigh 121 and I'm 14 years old almost 15 is this good?

If I am about 5'7 to 5'8 and I weigh 121 and I'm 14 years old almost 15 is this good?
Your bmi is 18.9, 44th percentile for your age group, which is healthy. I checked on this site:
http://kidshealth.org/parent/food/weight/bmi_charts.html