missed birth control pill, could I get pregnant?

Ha
I had sex two or three days ago and he came inside of me, I am on birth control, but last night my normal alarm didn't go off and I forgot to take my pill. Is there a chance I could get pregnant from this... Should I take plan B? 
Edit: I should add that I normally take my birth control pill at 10pm, and when I realized this morning, I took it at about 11:30am :/