I'm 23 and on birth control (Loestrin 24). Normally my periods are somewhat regular, but really light and short. Last month I didn't have one, but I did have some slight spotting before my period was supposed to come. This month my period also skipped.
I have no other symptoms of PCOS except some acne on my chin (but occasional breakouts are not uncommon for me, I have oily skin, plus an expired skin product and eating wheat with my allergy may have caused this).