I am 4 weeks pregnant. Well the pregnancy test and all the symptoms im.having say im pregnant... And my expected period was today. And it started. But isnt as heavy. But its not light. And i wouldnt say its spotting. But its not overly heavy so i know its not a miscarriage. I have no abdominal cramping- -like i do for normal periods; i do have bad lower back cramping though. And this started this afternoon. Usually my periods start overnight. Help me. What could this be and why