I Missed One Of My Blue Birth Control Pills During

I missed one of my blue birth control pills during the second week and had unprotected sex the same night. The next day when I realized that I had missed it, I took two pills, one for that day and the day before. However, there was approximately 20 hours or so in between having sex and taking the pills. Now I'm just starting the fourth week of pills, but for the past week or so my nipples have been sensitive to the touch. Is this a normal symptom of birth control or could I be pregnant?