It is possible to get a negative HPT and in fact be pregnant. But other things can make your period late; change in diet, losing weight, increase in exercise, stress--especially if you have been planning a wedding. White discharge can occur for different reasons also, it can be a signal that you are ovulating, it can increase due to pregnancy and I am sure there are many more reasons. If you still have not gotten a period in a week then I would consider taking another pregnancy test exactly as directed with first morning urine or contacting a Dr. to do a blood test.
you could well be i now a few people that havent showed on a home test i would nip to you doc an get a blood test done gud luck!