Scared of Pregnancy?

Okay ladies, I need some advice or whatever it may be.
My boyfriend and I had sex about a week ago and it was with a condom the first time. He came, took the condom off and we went on doing stuff we usually do (play video games, etc). Later on, things started getting heated up and we had sex again but without a condom. 
I took Plan B not even 24 hours after we had sex. 
What do you think my chances may be?