Unprotected Sex

So For My Birthday 10-24,1025,10-26 me and my partner had unprotected sex and multiple rounds all night and all morning he came in me so many times but later on 10-26 I bought a plan b … should it work ? & before that I was having pms & my period is irregular so the only time I know it’s coming on is when my boobs and nipples start getting sore , but before the sex I felt it now it’s gone … can I be pregnant? & I don’t know if I was ovulating or not because my period is SO IRREGULAR .. my period was supposed to start 10-15 but it’s not here yet .