You may be pregnant, get a urine test. Or it might just be that you are irregular for stopping he pill. I disagrre with Misskirsty. Having sex outside of marriage I don't agree with according to the Word. But if you do fall pregnant, I don't agree with killing the baby. I always support the baby, no matter what the parents did. If you are a single parent, not married or in a loveless situation, I still say keep the baby. LOVE LOVE LOVE. I don't know if STD's affect your periods. A baby is made in God's image!