Plan b and late period

Hello me and my boyfriend had sex about a week ago we didn’t use any protection so the next day first thing in the morning I went to get the morning after pill and was supposed to get my period a week after I am now 10 days late and I’m starting to really freak out I took a 3 pregnancy test and they came back negative but I’m still scared there is a chance I might be pregnant. Has anyone else had this problem???