I Had Sex On March 11 (day 12 Of My

i had sex on march 11 (day 12 of my 30 day cycle), and took a plan b pill an hour after intercourse. we also used the withdrawl method, no ejaculate was inside of me. it was day 21 (or march 22) when i had a cramp or two - i am guessing this was ovulation pains. i am worried about being pregnant, what are my odds? i have had no spotting - only an increase in acne and breast tenderness. my period is due in five days, is it too early for a pregnancy test?