Could EC Be The Cause For Irregular Periods?

hello, i took EC two months back and the two period cycles after that were fairly painful. On the 18 of June I had oral sex/making out in clothes but at no point was there direct genital contact or intercourse.I was expecting my period on the 5july but its 9th today .took an HPT but its negative (and that is almost 19 days after the risk) Is there a cause for worry?Is it EC messing with my period. I am v stressed out.