Given your avatar you seem to have a willingness to get into adult - but you wouldn't be the first to return years later wanting to remove all trace. You could use shystudent as a very niche and non-adult dating site but 18yet is obviously a site for pedos (or am I lacking in imagination?).
Maybe for 18-wheeled trucks? I'd stay way the f*$@ away from underage anything. Avoid it like the plague.