AF Question

Susan • Married for almost 3 years and TTC baby # 1
I was 8 days late to start AF...I finally started yesterday but it was very little. Pinkish in color, pretty bad cramps and low back pain. I normally have my period for 4-5 days and today it seems like it's already done. What's going on? I thought I would have a bad period since I was so late. Any ideas?