I had to wait until 3 days late to get a positive, and then it was so, light you could barely see it.
Sometimes the pregnancy test does not show up positive because the pregnancy hormone (hcg) levels are not high enough for the test to measure. The longer you wait the higher your hcg levels would be if you are pregnant and the more likely you would get a positive pregnancy test. My friend who was pregnant kept taking pregnancy tests and they were all negative until she was 3 months pregnant... her hormone levels just weren't high enough, and her baby is now 5 years old and very healthy so it doesn't mean anything is wrong. You could also not be pregnant and there are a few things like stress that make your period late. The first sign that most people get is breast soreness so if you have sore breast you are more likely to be pregnant. Just try to not stress about it and you can always ask your doctor to do a blood test or ultrasound if you do think your pregnant, they may want to wait a few weeks first.
You should take another test for sure. If its still negative, give it a couple more days and call your doctor. You can get a false neg on a test is why. Wish u luck.