Thanks for consulting. I have carefully worked through your case, and I can realize your health worries. Being your physician, I assure you not to worry as I will take care all of your medical concerns. there are certain facts about pregnancy which you need to know. a women can only get pregnant when a man ejaculates inside the women when she is in her fertile period approximately 8th to 20th day for her period. chances are high if it is around 14th day. so the rest of the time is safe period. there is almost no chance. when the women is having regular menstruation. For irregular menstruation it is difficult to find the fertile period. she has to use condom or oral contraceptive or emergency contraceptive post sex within 72 hours. the delay may be due to hormonal irregularity or psychological factor like stress or tension. Hope it helps. If you need further, detailed and quick assistance related to any health issues in future, feel free to ask me a question directly from my profile.