What Causes Delayed Periods After Taking Postinor?

Hi doctor, I had my usual period from feb 9th - 13th and had sex on wed 18th feb which I took postinor 2 pill about 2 hours after. This resulted in me getting my period 5 days after on Monday 23rd Feb - Friday 27th Feb. This was 2 periods in one month which both lasted 5 days each. However, one Tuesday 17th March I had sex again and took postinor 2 pill again and the following day I had unprotected sex and took no pill however my husband did not ejaculated in me. According to my period tracker app my period was due to start on Monday 23rd March from the last period I had which ended on Friday 27th Feb and it did not come on that date which was yesterday. Did the pill mess with my cycle?