Pregnant? but on pill

I just started taking the pill almost 2 weeks ago (so I passed my 7 day mark) last night my boyfriend and I had sex with no condom and he pulled out. Should I still take plan B? I heard you should wait a month to start having sex but I started the pill right after I finished ovulation. Is there a chance i could be pregnant? I know it's slim but it's my anxiety talking and I really need to know if I should take plan b or not