There is always a "possibility" as even when used 100% correctly the pill is only 99% effective.
That said it is very unlikely.
Ovulation typically occurs approx 14 days before your period and the pill usually prevents ovulation anyway.
Even so from sex on sunday to now you wouldn't actually be pregnant yet anyway as it takes 6-10 days for the egg to get fertilised and get to your uterus and implant.
So do I think you are pregnant - not really
do I know if you are pregnant - hell no idea - take a test hunni