Help pleaaaassseeeee

My cycle is normally 32-35 days the max I’ve seen is 36 I was supposed to get my period on the 6th (35 day of cycle) and I haven’t gotten it I took a pregnancy test on the 7th (cycle day 36) and it came out negative I’m on day 38 and still no period. I decided to start taking the pill when I got my period but I haven’t gotten it and decided to start placebo pills two days ago on the 7th (cycle day 36) and still nothing. This is my first time taking any birth control. I hadn’t taken any till two days ago and I started on the placebo instead of the hormone ones. And I had unprotected sex on the 23 of September (cycle day 22) took a plan b the next day (Cycle day 23) can someone explain?