hi im 20 years old and I missed my period 8 days ago. I had had sex a few times before that with my partner and I don't know when im fertile. I am on the pill (Normian 1) and haven't missed any of them. I am always on time and im worried. I am currently on champix to help me quit smoking I started that bout 1 month ago. I feel tired, really sick(not nausea), cramps really I just feel crappy. I have taken 2 pregnancy tests and they came up negative. What is your theory?