Plan B didn’t work??

Hi guys so I had sex on Monday night unprotected and he didn’t pull out. my ovulation begins tomorrow. I took a plan B pill first thing Tuesday morning but I didn’t eat anything at all. I know taking your pills with food is VITAL because it helps get the medication in your blood stream better. I’ve taken the plan B pill before and the side effects of it have always been noticeable but this time it does not feel the same at all. I haven’t had any cramping or headaches. I feel nauseous when working out and a little dizzy but that’s it. Is there ANY chance maybe the pill didn’t work? I’m scared. Thanks in advance! Any advice is appreciated!