Thanks for trusting ATD about your health care.
I can understand your concerns.
The chances of pregnancy is almost nil before your period date because these are the safe days( less fertile days) after post ovulation.
If you get your menses after sex and your period was normal then there is no chance of pregnancy because there is no endometrial tissue present( slaughter out during period) to implant fertilized egg.
Hope it is useful, feel free to discuss more.
These Q&A’s are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.