@ What age do people grow until??
Where Rob generally It tend to be 18-20 here..But its different in every country according to its Environment and Diet and Ect...
Medically its depend on secretion of your GH(Growth Hormone)..
Physiologically GH secrets whole life..But it stop its function regarding to Growth(Height) near 20 years of age..Although its individually different for every person..
You are 15 years old now??If yes then you have more 3-4 hours to grow Don't worry..Lol..
Hope My post helped you...
I would worry son because according to him you stopped growing!