Is Pregnancy Possible Despite Taking Plan B After Unprotected Intercourse?

Hello, I had sex on March 1st, 2015 and my boyfriend intentionally tried to get me pregnant. My last period was on February 18th, 2015, so I was expected to ovulate around March 4th, 2015. I took a Plan B test on March 3rd, 2015 and ever since I took the pill, I have been experiencing pink discharge and the normal clear discharge every so often. My next period is suppose to come on March 18th, 2015. Could the Plan B pill not had worked (causing me to be pregnant) or could it just be a sign of my period about to come earlier than expected?