Chemical Pregnancy

I was searching topics on pregnancy and I found an article about chemical pregnancy. After reading it, it had me thinking about my recent period. I was a week late last month and I'm never late or have irregular periods. It seems like I could have had a chemical pregnancy but I never took a test to see if I was late due to pregnancy. We are TTC and that was our first month. Has anyone had one or believe I could have miscarried and not known? I did miscarry in 2004, or so my doctor was led to believe due to blood tests, but I was not late at that time since I was on BC and I had a really strange/heavy period that month.