I've just turn 17 and am worried about my puberty. I have underarm hair, my voice has broken and is distinctly deeper than before, and I have thick pubic hair. But when I look in the mirror I look like a 14 year old. I don't have facial hair and have a baby face.
Every person is different. You happen to be the type to look young for your age. At this moment in time you see that as a detriment because you are in a rush to be seen as an adult. About half-way through your life you are going to be happy that you aren't looking as old as your peers.
Facial hair starts showing up during stage four, but it doesn't fully develop until after you reach stage five. It is also in the latter part of stage four that the chin widens to give you a more manly look. So while it might not be happening as quickly as you would like, there isn't anything wrong with your development.