Hi there and welcome. Well, it is indeed not perfect timing to conceive but you are right, you never know. If a pregnancy would be horrible, then go ahead and take Plan B. It will cause your period to be irregular for a cycle or two but then you won't have to worry. But remember, you have to take plan B within 72 hours. good luck
You should to use the next day pill.. but the anticonceptional pill was takes righ had less risk... but pay atentioon with another simptoms