Will The Plan B Tablet Affects My Periods?

Hi, I'm 23 after I gave birth in 2009 I was left with a bleeding problem I spent like 2 years bleeding constantly first the doctors said it was due to a hormonal pRoblem and then because the last time they said that I had a big bruise that was causing the bleeding know I have my regular period well the last 2months but I took the plan b pill twice these week and I want to know if it's going to harm me