It is possible to experience a delay in your period while taking certain medications, such as birth control pills. If you have taken a pregnancy test and it came back negative, it is likely that the delay is due to the effects of the medication. Many women who take these pills regularly may experience changes in their menstrual cycle, including lighter or irregular periods. This is a common side effect and is not usually a cause for concern. If you have any further questions or concerns, it is always best to consult with a healthcare professional for personalized advice.