First of all, this is only kind of uncommon. It doesn't mean that you won't go through, just on the upper end of a late bloomer. Have you had ANY signs of puberty? Hair anywhere? Voice? Growth spurts? If you can't find any evidence that you have started, then I would tell my parents or a doctor.
It doesn't really even need to be a parent. If you happen to be going to the doctor for a physical or anything, ask him then. For me, it's easier to ask those questions to people I don't really know or regularly associate with. If you were to want to ask your parents, just casually bring it up. Maybe it would be easier to tell only 1 parent instead of both, and then have them communicate about it not in your prescence. Just take them aside and say "Hey, mom/dad, I'm not all too sure my puberty is going like it should be. Maybe you could take me to see a doctor?" That will likely evolve into a slightly embarrasing conversation, but there is really no way around that.
Hope all turns out well, and I wouldn't stress about it too much if I were you. Stress gives you acne.