Am I pregnant?

I took a plan B 3 weeks ago. About 6 days later I had bleeding. It was like a light period and only lasted about 2 days. A few days ago had heavy watery discharge and now not a lot of discharge. I’m 4 days late on my period and my period is usually irregular but it’s still worrying. I don’t know if it is the plan B pill or if i am pregnant. Please help i don’t want to be pregnant. Hopefully this is just a horrible pregnancy scare and it’s just my mind playing tricks.