Are you guys sure the condom broke? Because you guys don’t sound so certain about it.
Plan B has an extreme amount of hormones, so it’s very likely you will experience side effects because you took it. Because it’s such a large dose it’s possible to still experience side effects weeks (or month) into the future. Please read the pamphlet before you take something.
Taking plan B doesn’t mean you are automatically safe. It will prevent pregnancy by preventing ovulation but if you were already ovulating it won’t do anything. There is no point in taking a pregnancy test now, you need to wait at least 21 days for accurate results and then take a test.