Took plan B

I had unprotected sex with my boyfriend Sunday night. We both think he came inside of me but weren't sure since we were super tired. I took plan b the next night. Within two hours I threw up alittle bit. How will I know if it worked or not? I'm supposed to have my period in two weeks and I'm ovulating now. Also we have unprotected sex all the time and we use the pullout method. Last week we had sex also and he pulled out but his cum was all over my vagina but not inside. I have been feeling nauseous and tired all day. Is this normal to feel this way? Is there a possibility that I can be pregnant?