Plan b ?

Patient: I had my period on dec 9 had sex the on the 14th and took plan b 6 hours later i know i am safe bc they says its not most likely to get prengant couple days after ur period but i took it to be safe ,then again the 18 but he didnt cum but then again on the 19th then i started spotting today on the 20th am i still safe from taking the plan b?