Can Plan B Cause Delayed Periods?

Hi. My name is Amanda, I am 18. I had my period at the end of February and then I had to take plan b around the beginning-ish of March, maybe the 6th or 7th I don t remember the exact day, and it gave me my period again about a week later. And the end of March has come and passed and I haven t gotten my period like I do at the end of every month. I took a preg test on April 1st and it was negative. Should I be worried? Can plan b make you late? I ve read it can make you late, or even skip. Also I have taken plan b twice prior to this time, if that means anything. Thank you, Amanda