Plan B and Birth Control

I'm 17, and made an ignorant mistake Saturday afternoon. I'm on birth control, have been for almost 3 years now. I take it at the same time every night and never miss a pill. My boyfriend and I always use protection, except for Saturday- we didn't use a condom. He also came inside of me, of which came out (tmi, sorry :(). I was so worried, I went and took the plan B around 6PM that night. Now I've been having slight nausea and am worried sick. Am I pregnant? My period will come on the 23rd. Should I be worried since I'm on both birth control and took plan B?