I've had unprotected sex on the 27th of December. My period was 9 days late. I started light bleeding on the 6th of January and ended on the 9th. My periods are usually longer than that and slightly heavy. That made me think about implantation bleeding but I could be wrong. I did research on implantation bleeding and it says that people sometimes confuse it with a period. It has been 3 weeks and 3 days. I've taken pregnancy tests but they've all come out negative. If anyone has an idea or any suggestions, I'd be happy to hear them.