Yeah I look younger too (or so I think, not really sure about that since i bulked up). Usually I get mistaken to be a couple years younger because I don't have any facial hair (i'm blond)..
Once when flying from NYC to Europe while being 16 (a month shy from 17), there was a cutie next to me who looked about 19-20 so I started talking and kicking it off with her right away. Turns out she was 25
I asked her how old she thought I was, and she said "21? Nooo. You must be 19-20. You look pretty young." That really soothed and stroked my ego. It was slightly unreal though, we were drinking wine that she ordered and ended up making out heavily in the seats under a blanket and rubbing each other, and then fulfilled my fantasy of getting a BJ in an airplane.
Never contacted her, but still carry her name, phone and email that she wrote down -- in my wallet -- just because that gave me alotta hope regarding my age self-consciousness. She was also half African so I also broke the cultural barrier I'd been having (I'm weirdly attracted to chocolate skinned women...)
Well, anyway, hope this story of 'young' looks encourages some of you to not let the age issue be a barrier (it's not, really, as long as you don't make it one -- which is really hard yet COMPLETELY DOABLE.)