It's possible still that you can be. The pill only has a success rate of around 85%. However, it's also possible that it just messed up your cycle--- Plan B should be used as few times as possible (less than 2x a year) because the dose of hormones is so bad for the body. Because it's so high, it can cause a few months of your cycles to be messed up. Wait till around the time you got your period last month (I assume somewhere around the 20th) and see if you get it. If not, take a pregnancy test with first morning urine. You need to also be using condoms and birth control if you don't want to become pregnant.
thanks so much for a response