Possible Miscarriage?

My period was due on Friday of last week and usually I run like clockwork. I was pretty positive that I was pregnant because I had experienced some breast tenderness and discharge from my nipples, and we had intercourse on my ovulation day. Yesterday I experienced some mild cramping on my right side and woke up this morning with a terrible migrane that lasted 5 hours. I had also started bleeding pretty heavily. My husband and I weren't actively trying to get pregnant since we are not in an ideal financial place to raise a family yet, but I am curious if this was just a late period or a miscarriage? Can they happen so early? What is your experience?