Chances??

Hi!! I had unprotected sex and he pulled out. I have been on the birth control pill for a couple of months now and haven’t missed a pill yet (yay for me!!). I am a worrier and I like to overthink everything in life so obviously for this I began to think I was going to get pregnant right away so a couple hours after sex I got Plan B and took it. I know no birth control is 100% effective other than abstinence but what do you think my chances are?? I am on my second week of pills for my period. Do I wait until my fourth week where I take the red/brown pills and see if I get my period?? Thanks so much ladies!! All the advice you can give me and guidance would really help me out xoxo