Everyone ages differently!

I am talking about biological age.
People say males stop growing at the age of 21, so biologically it could mean 22-25 right?? possible?!? I remember when I used to be very active up until 18. I wish I was aware about the 21 age limit so that I could have continued daily exercise and eat extra proteins. (feeling sad!) I am grateful for my current height but I am still so angry for not doing the best I can for myself! I will begin to exercise daily and eat very healthy I promise myself! I must grow! For all of you who are not physically active and near or under the 21 age, Please do something about it while you still can! Lets do it, all of us! Everyone should be be active anyways, be active + nutrition because I read that when you are active you feel good and when you feel good your posture will improve, thus standing taller and less slouching (damn computers!)
Back to my main point. Is there still hope for growing after age 21-23-25?

P.S. -short story-
When I was 16 I ask my gym teacher if I will keep growing or when do I stop growing and she told me that I’m done…at age 16? yea right lady. I think she said that because she was short and she might have thought that I was tugging her tail or something but at that time I really had no idea, so that false fact stuck with me in a way that discouraged me and NOT thrive/motivate/ambition/inspire/all the goodness. I never really researched/googled my curiosities (yay FunAdvice!) Teachers are suppose to input positive ideas/advice into young minds so that they can give us hope to thrive for more. Most teachers did their job but this teacher was for gym/health and here I am… concerned about height/health. When I think back about it I am furious, mostly my mistake for being so gullible but Mainly at …forget it =P
I’m not trying to lecture everyone about this but I just want people to be aware that what we teach kids can have an impact on them as it did on me. Thanks for understanding. Get/Stay healthy!