I haven't got mine in two years, am going to the GYN next month to discuss (Not because I'm alarmed by the lack of it (although my husband is), it has more to do with the fact that I should bear a child some day in the near future). Reasons are the same that everyone else mentioned: low body weight and excessive training. So don't feel like you are alone.

As for the acne issue, haven't had anything outside of the norm there but I do use really good facial products - mostly products from Origins. I use a scrub in the morning and a more gentle cleanser at night.