Unprotected sex 3 weeks ago but no period?

There are many reasons why you may not have gotten your period yet, including:

* Pregnancy: If you had unprotected sex, there is a chance that you could be pregnant.

* Stress: Stress can affect your menstrual cycle, causing your period to be late or irregular.

* Diet and exercise: Drastic changes in diet or exercise can also affect your menstrual cycle.

* Medications: Some medications, such as birth control pills and antibiotics, can also cause your period to be late.

* Underlying medical conditions: Some underlying medical conditions, such as thyroid problems or PCOS, can also cause irregular periods.

If you are concerned about your missed period, it is important to see your doctor to rule out pregnancy or any other underlying medical conditions.