I understand EXACTLY where you are coming from because I have had the same issue all my professional life. People say "wow" and they say it as if it's a compliment but I almost feel like its a curse to look younger.
I think part of it will also be your personality as it grows. Just don't get into being a submissive and passive person. That would make everyone take advantage of you.
I'd say you look 17-19 or so. Not that young. And you are cute! (Not in a lesbian way) You seem to have a doll like appearance I am sure guys will like you. Besides guys don't mind being older. Guys around your age might not want a much younger girl but once men start to hit their late 20s and up they like younger girls. I am 20. and I get hit on a lot by much older men.
Plus it is about maturity. If you act mature and people find out your real age they won't mind.
Also, if you look young now and take care of yourself you may still look younger when you start to hit the age where you want to look younger than you are, like 30s or so. A woman who is in her early 20s does not want to be mistaken for a teenager. But a woman in her early 30s would love to be mistaken for a woman in her 20s, and so on.