My period doesn't come at the same date/time every month, it comes either 1 week before or 1 week after. And sometimes even with a difference of 10 days. But there are times when I completely miss a period for the whole month and then it comes a month after but at a very different date. I am married but I use protection during sex. What could be the reason for the irregular periods ? This happened even when I was not married. But after marriage, when this is happening, I worry about the pregnancy and when I find out it's negative, it's a bit disappointing. Please help me.