Unprotected 11 12 & 13 days before period due, what are the chances of being pregnant?

i am ussually very regular with my periods always on the 5th 6th or 7th of each month but i am now at least 2 days late, me and my husband had unprotected 11, 12 and 13 days before i was due, i am getting some twinges like i am about to start my period