Ermerged, I have the exact same thing! Mostly naturally though, cuz I haven't taken any hormones to alter my body, but I will be with people, like when I was at bandcamp for example, and we have a fun time together, and then I tell them I'm 18, and they are like "You're 18!? No way! Are you joking?" Same thing when I was at my old job, and told my cowerkers, a lot of them who friendly would pick on me, insisted I was just joking back at them, cuz they were 16 and 17. People online, who haven't even seen my face, I tell them I'm 18, same responce "Really? I would have guessed you like 14" XD (be in mind these people didn't see me though). Bought Skyrim at Walmart, which is for 17+ and the cashier asked for my idea, and was like "ok, just making sure, you don't look 18." So yeah, nobody believes me when I tell them that. However for me, I kinda like that. I find the whole matter funny, and it's fun to see their reactions. And besides, wouldn't it be a good thing that people think of you younger than older anyways?