Has your doctor или parents сказал(-а) anything to Ты about it? Are Ты otherwise healthy; ie, you're sleeping enough and active and able to get through the school day?
You're still growing, so I'm guessing that your weight will be in flux for a while longer. I'm the same height as you, but I'm ahem, way older, and I'm 140 lbs., and that's kind of the heavier end of the spectrum.
I wouldn't be too concerned unless you've been told otherwise. As a contrast, my daughter is 17, is 5' 10" and weighs 100 lbs. She's been told to eat еще than once a week.