Plan B

I need some advice, I took Plan B (Levenolle) on Tuesday 21st June around 10:30am as I had sex the Monday evening. We used a condom and it didn't split as I asked him, it's the first time a guy has ever came inside me with a condom on so I panicked. I just wanted to know if I could be pregnant and is Plan B really effective? I'm worried incase it doesn't work. Any advice would be helpful, thank you! 😊