Help please! 😣

I had unprotected sex on April 23, right after my period ended and toke Plan B the night of the 26th. About a week or two later I had what I thought was an early period, super heavy flow and lasted about 4 days. But I am now 5 days late for my regular period and My abdomen has been hard and upset. Idk if maybe the pill didn't work after all or if it's
Something else.Â