Plan B question ASAP

Kasy

Hey ladies, I have a question regarding Plan B. I took a plan on November 6th and I got my period regularly like schedule on November 19th but it last 2 weeks making my period to finish on Dec 1st. But on my <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">period app</a> it’s saying that my period should start again on Dec 19th but I’m late by 3 days. It that normal?