I was late on my last period by about two and a half days. I'm sexually active but am on birth control and very careful when it comes to sex. I just got done with finals, which was intense stress and caused me to change my sleeping schedule dramatically. So after I finally got my period, It was just very dark, brownish almost, and very gooey. The bleeding lasted around 3 days and it never used the whole tampon, only about half. Usually my periods last around 4 days. Could I be pregnant? The only reason I'm concerned is because one early morning I felt a bit nauseous and I have been very emotional. ( Although I've only been off my period for about 2 days so I might be PMS) and im incredibly aware of my tummy.