Chances of a baby?

My boyfriend & I had unprotected sex Saturday , Sunday following I took a plan b pill. We didn't use a condom and I'm not on any form of birth control. Last night ( Wednesday ) he finished in me and when I got home I noticed that my underwear were soaked completely and it also went through my leggings. We both don't mind a baby and my fertile window is active. But will another plan b work considering I just took one ? And what are my chances of getting pregnant ?