I often see people say they are "only" xx.
I'd like to caution against saying that for a couple of reasons.
You especially do not want to say it in situtations such as, "I'd like to accomplish this but I cannot because I am only 17" or when answeering a questions with "Well, I'm only 17."
Never say anything that takes personal power from yourself. Especially never say it if it denigrates yourself. Language is vital to your personal growth, especially when it goes to who you are.
Similarly, avoid saying, "I accomplished this and I'm only 17," because that could be vainglorious and gets close to that first deadly sin.
And, question whether you might even be saying "only 17" because you want to grow up faster. Find the joy in every moment at every age, and don't rush anything. (That might even be related to that third deadly sin.) Instead, when you want to make a point about your age, say "I am 17." That clearly establishes grounding and can build self-confidence. There is power in the words "I am." Don't diminish it with a qualifier such as "only."
That said, I applaud the young folk who are here to experience their potential. And I look forward to reading posts of their accomplishments five years, ten years, twenty years from now.
While learning is lifelong, and many people will visit here continuously throughout their lives, I look forward to what returning folks have to say.
Someone might say that sharing accomplishments is vainglorious, but when it goes to motivating and inspiring others, I am all for it. Besides, sometimes it is fun to toot your own horn.