Should I take plan b

I missed 3 days of my birth control (ortho cyclen) while I was away on a camping trip. But the minute I got home I got back on track. 5 days later I had sex with my boyfriend and he came inside. The birth control instructions said that you should wait 7 days before having unprotected sex. BUT, it was also at the end of my period. So I'm not sure if it's worth buying plan b. Please help!!