I Have Sex On 31 August Morning Time And I

I have sex on 31 august morning time and I took both of the pills of P2 at the same time the next day after sex on 01 September , I felt a lot of dizziness which left after a few hours...after a few days I started feeling a lot of breast pain up to now today..I expected my periods on the 18 September which has not come up to now...could I be pregnant because I have no periods yet past expected date? it was my first time to swallow the tablets