Plan B

I took plan B a day after unprotected sex on Friday, Jan 4th. It’s been a little over a week and I haven’t had any symptoms. No bleeding, no nausea. Just headaches and really emotional. I’ve taken it before, and exactly a week after each time I normally bleed. My period is due in 3 days. Maybe it’s just delaying my period. I’m in college so I’m hoping that I’m not pregnant just yet. Are the chances high of plan B possibly failing? I’m freaking out 😭