I had my period the beginning of dec. (around the 5th I think) and I had sex on Sunday the 18 around 2:30am. I got the pill the next day after school and took the first pill at 3:30pm but accidentally took the next pill at 2:30am. Since then I've been really nervous because my period hasn't arrived event though it doesn't come till January, and I heard stress would just push it back. I guess my question is is there a chance tht I'm pregnant. Today I had cramps, backache, and dizziness which is a first since taking the pill. I've had diarrhea once or twice before today. Please help.