38 Days Late!!?

My period is 38 Days late!!! I had unprotected sex on 10/6, he did not cum in me (he came on me) but I took a Plan B just in case. My period was supposed to start on 10/21 but it didn’t and I did experience breast tenderness for quite a few days before and after 10/21 but my period still never came. I tested and the test came out negative but my period still has not started and idk why. I’m not experiencing any alarming signs/symptoms or anything but where is my period??

P.S. that was my 5th time taking a Plan B (which is so terrible I know, please no judgement)