Hello, I'm a bit scared because my menstruation does not come. I'am 18 years old and I have a boyfriend. We had sex the last month but we used a condom. And everything was ok normally. My menstrual cycle is not regular but now I'am a few days to late and I don't know what to do. My previous menstruation was the 13th of December until the 16th. Now I have some stress for the exams at school. A week ago I had abdominal pain and then I thought my menstruation would come the next day, but it wasn't. And since a few days I sometimes have a headache, but that I always have a day before my menstruation. Can you help me please? Is this normal? Thank you.