I have been regularly having sex with one guy, but never use a condom. He usually pulls out, but he wasn't sure like twice last month. I took a lot of vitamin c, because my period was 4 days late. It came, but it would start and stop for a week. This month, I am 11 days late. I tested at 3 and 5 days late, both tests were negative. My boobs are super sore, which NEVER happens. I haven't had more stress than normal. Is it possible it was a false negative?