Help me

Hi I was wondering how easy can you get pregnant from precum I just got my third rod since 2015 out I’m 20 year old and started the yasmin pill last Monday. I have had sex twice on the weekend with my boyfriend with no condom and the pull out method how much percentage can I be pregnant? The pill has made me very nauseous last week I threw up one day and had the runs two days this week. I’m scared