2 days in, cramping, no period yet!

Of course it's too early to say anything yet, but my period was supposed to start two days ago Thursday, I'm cramping and having headaches like with all my periods, but no period yet. Usually I may cramp a little but the day before. But the way I'm cramping now, my period should be going. I'm always obsessing if I'm pregnant if my period doesn't come exactly since my husband and I are not on any real birth control. My periods are usually right on the dot, 28 days. We'll see later today.