My boyfriend and I had unprotected sex on 13th March while i was on my periods and it was the 1st day of my periods. The next day i.e, on 14th March i took an Emergency Contraceptive pill. Taking the Emergency  Contraceptive  while i was on my periods elongated my periods and my periods lasted for 8 days (they're usually 4-5 days long). After a month I took a pregnancy test which came out to be negative but I am late for my periods for 4 days now and am really worried that i might be pregnant. I have been noticing symptoms such as mild cramps and tender breasts but I've noticed no bleeding. 

Can I be pregnant?