Is this possible?

I had a period Sept 1 and it lasted 7 days. 4 days later, I had another period that lasted 4 or 5 days. Since I had two periods last month, is it possible that I'll skip this month? I've been spotting the past few days (old blood & barely any), have had VERY mild cramping (barely noticeable), and a bit nauseas tonight. But no period at all.... I'm not on birth control, so that's not causing it.... I just don't know why this is happening. It's never happened before.