You're not alone! Sounds like a scary situation, but you did the right thing with taking Plan B as soon as you could. The chances of pregnancy are quite a bit lower since your partner did not ejaculate, but you probably know that it isn't a guarantee.
Plan B can cause some spotting for a few days before your actual period comes so that could explain the pink discharge. Also, Plan B can also cause your period to become even more irregular.
For now, you should take a home pregnancy test and/or check with your doctor, but you might have to simply wait it out.
Here's a similar question that someone on EmpowHER asked, so maybe something here will help: https://www.empowher.com/community/ask/irregular-period-prior-taking-plan-bquestions-about-what-expect-now
Let us know how it goes!