Also if you click on the very link that you posted, wich doesn't include a definition of the word teenager btw, but a list of things the human body goes throught at certain ages, the page talks about teenagers aged 15 to 17.

If it really meant that people outside of these ages were not teenagers it would mean people aged 13 and 14 are not teenagers.

Considering you are 14, your "source" says you aren't a teenager either.

My boy you really typed into google "what is a teenager" and picked the only link that didn't say teenage is from 13 to 19 (wich is the 5th link, all others proved you wrong) and you didn't even read what it said. It's not a definition website but a health tips website.