WHY AM I SPOTTING

Hey,

Ive been on the pill for almost a year. I am sexually active and use the pill as my only for of contraception other then always withdrawaling during sex. For im 12 days post period and im spotting! Why! This has happened once before about 5 days ago also during this cycle. I just dont understand. And im really stressing out that im pregant. Although ive never missed a pill and i havent taken any late.

Why would i be spotting more then once during my cycle?

Please help.