I'm 17 years old and I've been having a lot of inconsistencies with my periods for a few years now. I don't really know where to start, so here goes... My first period was 9/28/04 and my cycles were always 30 days in length until March 2008. After I missed it 9 months in a row, I finally got my period again in January 2009. At first, I thought it was some kind of sympathy pregnancy for a friend of mine who got pregnant in March 2008, but then later in 2009, I started skipping periods again. The cycles also varied greatly in length from 29-45 days. My periods were never heavy or painful after not having one for several months; they've actually been much lighter since I've been missing some. I don't think my uterine lining thickens at all when I don't have periods. I guess my question is, could I still have endometriosis without the "classic" symptoms?