Why?

I started my period today.  I didn't cry, but I almost did. I didn't really think I was pregnant this month since I hadn't gotten a positive OPK, but still every time I start my period I feel sad.

Lou tried to remind me that for a long time I never started on my own...I know the fact that I'm having a period has got to be good.  I wish I just knew:

Why I only had a 21 day cycle last month and this time it was a 32 day cycle. 

Why last month I ovulated on day 12 and some months I ovulate on day 16 or 14 or 21.

Why for my whole life when I didn't care about having a period I was always having one (every month like clock work) and now I can't have a normal period to save my life.

Why do some girls get pregnant the first time they have sex and some girls (me) can't?

Why does all this fertility stuff have to be so hard/emotional/expensive/sad/mad/crazy?