Scared and Suicidal

I took a preg test and it said negative. I get so worried that I don't believe it I'm too scared to take another one. My period is late by 5 days after having a irregular period bc of plan b making it either start early or be late. Idk if it's the plan b making me late but I can't be pregnant it would end my life. I'm 17 and going to be a senior in high school I can't do this I have a college basketball career and I feel like I gave it up over stupid decisions