Am I pregnant?

Hi.. I am 28.. I am having irregular periods for 4-5 months. My overall cycle duration has increased to 40-54 days.. the irregularity started on nov/dec.. nov(17-21), Jan (10-13), Feb(17-23), April (11-14). last period was on 11 th April and ended on 14th. I had unprotected sex on 15th. I thought it would be safe .. but I bleed during sex, so we stopped. He had ejaculated inside me two times.. fearfully I took two pills of unwanted 72 , one within 3 hr , another after 24-26 hr of the 1st one.. Now on 22nd April, I saw some spotting but blackish. Today it was kind of brownish.. Am I pregnant? When can I test for pregnancy?