Ah, ok. Don't know then. It might just be a hormone imbalance due to stress. Before I was TTC (but at a stage when I was kind of hoping for an accident) I was 26 days late for a period with all the symptoms in the book, pretty much, bar sickness. The doctor told me that it was a hormone imbalance and gave me some painkillers since the resulting period was a lot more painful than mine usually are. If you are still getting negative tests at the end of the week and symptoms persist, I think it would be worth your while going to your doctor.