Can Pregnancy Still Happen After Missing Birth Control Pills?

+hello i am an18 year old female and about 3 days ago i missed one of my errin (birth control) pills and ever since then ive been taking a pill at the same time everyday and tonight me and my boyfriend had sex with a condom slipped off as he was ejaculating and the condom slipped off he wasnt aware of it when it happened and he ejaculated inside what are the chances of me being pregnant and if i take 2 pills today will it help