Stopping BC

I stopped taking my BC, I was having some insane side effects from it. The brand was Orsythia, anyway I know it's not a huge probability but I had intercourse last night without protection and I know that sperm can stay 'in you' for up to about 3 days (I believe 3 is the correct number). My question is what's the possibility of me becoming pregnant, I know I should just wait and pick up a test or whatever but I wanted to hear experiences from others as well! Please respond thank you.