How To Confirm A Period?

Hi, On October 4th I took Plan B after having unprotected sex. I was not supposed to get my period until October 20, but got it October 10th. I assumed it was from the hormone increase. I then got my period on November 4th. I had sex on November 12th, although he did not ejaculate, I was worried about pre cum and took plan b on November 15th. I started bleeding again on November 21. Could it be my period again or should I be worried its implantation bleeding?