Worried

Okay so I had sex Monday afternoon and I think some semen got on me (but he wore a condom) my last period was June 5th... I'm not on my fertile week this week as this is next week... I'm freaking out majorly!!! I took plan b today at around 10:30am but I'm paranoid incase it doesn't work or anything of the sort... I can't tell my mum cause they guy isn't my boyfriend & if she finds I've been having sex without being in a relationship she'll literally disown me... I'm so stuck on what to do! I've been feeling sick and I'm so tired but I don't know if they're the side effects from the levonelle!! Can someone please give me advice I'm so scared