See u took ipills ,so u had a withdrawal bleeding on 18th ,so now ur periods will be delayed as ur Menstrual cycle has been disturbed due to ipills,u may either wait for your periods now or do a Urine
pregnancy test done to see for any pregnancy if u have any doubts,you may alternatively get a betahcg blood pregnancy test done to see for pregnancy if ur periods are delayed by more than two to three weeks.