Could The Delayed Periods Be Due To Plan B??

I took Plan B September 24th and started my period on October 2nd. I had sex for the first time since then around November 17th and since then a handful of times. I have not had a period since October, but heard Plan B can affect your next period. I took a pregnancy test last Tuesday night (Nov 30th) but it was negative. Could Plan B causing this or should I take another test?