Paranoid or Possible?

So I have been reading up on the effectiveness of the pill and it says that its practically impossible to get pregnant on the pill. I had my period on Feb. 3-9 I believe and started taking my pill that Friday. I had been taking my pill for 6 days (the week starting up again after the sugar pills) and my SO finished inside of me. I know the chances are probably slim to none but I have been feeling a lot of weird symptoms that are also early pregnancy symptoms. Is it possible to still get pregnant while on the pill if he finishes inside me? Thanks in advance!