Okay so I had my son almost three months ago, and my first period I had after delivery was 7 weeks after, it lasted my usual 7 days. I just started my period abruptly on the 20th with no sign I was going to be starting, other than my calanders I have. GLOW said I was due the 24th another said the 20th. So I had become extremely nervous because glow hadn't been showing my fertile weeks. Finally did, and the one time I had unprotected sex it was during that week.

Obviously I'm not pregnant, but I'm curious what would cause my cycle to be irregular? Is it the birth of my son? I normally last seven days not four. Medium flow with minimal clots. TMI I know but I was concerned.