Irregular periods

Kelly • Teacher & Wife• 9/29/17 •Pregnant with baby #1• PCOS fighter.

I was on birth control for 8 years and got off of it 4 months ago. I got one period in January and I was supposed to get it 6 days ago, but nothing. I took a pregnancy test and it was negative. Any ideas why it could be late? Has anyone else had this problem? We have been trying to get pregnant for about 2 months now.