Missed period, light bleeding and still it is negative pregnancy test. Sometimes, negative pregnancy test doesn’t necessarily mean that you are not pregnant. There are several reasons for missed period, light bleeding and negative pregnancy test, such as the test results might be wrong, you took the test wrong, or you took the test too early. Whether or not you want to become pregnant, these conflicting outcomes can lead to a great amount of stress, confusion and worry for any woman. - http://goo.gl/6IVIT
Thank you for this post. Its soo important to not incline towards conclusions. It could be due to anything! The reason could be implantation bleeding as well. Therefore, do visit the doctor. I hope there is nothing serious. Other than this it is also very important to take a good quality test. Good luck to you.