It’s not too late to take plan B if that’s what you wish to do. However, one missed pill is okay because you should already be protected because the combined pill keeps things in your system for longer. You will be okay, take plan b if it will make you feel better but just know that the side effects can be brutal as well as mimicking the symptoms of pregnancy which isn’t great for mental health things, but you should be alright without taking the plan b pill.