LaBonita, pregnancy can occur at any time because the human body is not 100% predictable. I know a woman who became pregnant even though she had not had a period in 5 years and thought it was menopause. I know another woman who conceived even though she was already pregnant. She carried two babies with different due dates. My son was conceived 3 days after my period ended, and my periods ran like clockwork! Unless you've been charting your ovulation with a test kit, then it's difficult to know for sure. Also, sperm can live in your reproductive tract for up to 5 days, increasing your chances.
You must know there's a slight chance, or you would not have made the post. See your doctor for advice. No one else can help you.
Good luck