My boyfriend and I have had sex using the withdrawal method a few times here in the past month. yesterday, I came home from my boyfriends after we had sex using the withdrawal method and I had cramps. The cramps ended up being so bad it woke me up in the middle of the night, so I went to the bathroom and I was bleeding so it seems like I started my period. I'm still bleeding like a period today, But my period shouldn't have started for 3 or 4 more days. My period is irregular but typically starts around the 19th at the earliest and the 24th at the latest. Is it abnormal that it came early? The flow isn't as heavy as usually seems either.