You havent came on your period for over a week and you did pregnancy test yesterday but im not pregnant so why on?

The reasons why your period is late but a pregnancy test is negative could be:

- Pregnancy: While a negative pregnancy test usually means you are not pregnant, it is possible to get a false negative result, especially if the test was taken too early or if the instructions were not followed properly. To be certain, you should repeat the pregnancy test in a few days or weeks. If you are still getting negative results but continue to miss your periods, it's important to see a doctor to rule out any other potential causes.

- Hormonal imbalances: Various hormonal imbalances can disrupt your menstrual cycle, leading to missed or delayed periods. These imbalances can be caused by a number of factors, such as thyroid issues, polycystic ovary syndrome (PCOS), or stress.

- Lifestyle factors: Certain lifestyle factors can also affect your menstrual cycle. For instance, excessive exercise, significant weight loss or gain, and poor diet can all contribute to missed periods.

- Certain medications: Some medications, such as birth control pills, hormonal treatments, or certain antidepressants can disrupt the menstrual cycle, causing missed periods.

- Medical conditions: Some medical conditions, such as uterine fibroids, endometriosis, or pelvic inflammatory disease (PID) can cause menstrual irregularities, including missed periods.