I got my normal period in March, but it skipped April. Later on around the end of April, I had unprotected sex but too Postinor-2 immediately after. I got my period 5 days later in May. Period in June was normal but my period for July seemed shorter than usual. I usually bleed for 7-8 days but I only bled for 5-6 days in July. Is it possible for me to be pregnant? It seems impossible to me but I have a little doubt in head. I have tested negative 3 times but I am afraid that it is a false negative as I have heard how there are women who tested negative throughout their whole pregnancy.