Does Plan B One Step Really Work???

I Took Plan B Like 15 Mins After Sex . This Was 2 Weeks And A Day Ago, July 17th. I'm So Paranoid That It Didn't Work And I Can't Stop Googling Stuff About It. Imma Drive Myself Crazy..Please Give Me Some Advice. I Feel Weird. Like My Stomach Feels Weird Every Now And Then And I Feel A Lil Nauseous. It Was My First Time Having Sex And There Was No Protection..I Was Dumb For That. Does Plan B Really Work? Wat Are The Chances For It Not Working? Anyone Who Has Takin Plan B One Step Before, What Were Your Experiences And Did It Work For You? Just Anything So I Could Feel Less Stressed..Thank You.