I'm normally very regular with my cycle. 3-4 days at most at the very beginning of the month. Typically the second or third. Although last month I was a week in the beginning of the month, and then I barely spotted for two days in the very end. I still haven't had my period or any pms. I'm trying not to stress about it because I don't want my partner to know that I haven't had it just yet. Are there any reasons to why this is happening??