Periods can be late for lots of reasons. Things like changes in routine, stress, illness, weight gain or loss, or just a blip in the hormones. Most women are occasionally late and periods don't always work like clockwork even if it's the norm for someone. Pregnancy tests are very accurate and symptoms of pregnancy are very much like symptoms of PMS. Also, if a women doesn't have enough hormones to trigger the pregnancy test, they don't enough to cause pregnancy symptoms. Things like pregnancy nausea starts at 6 to 7 weeks of pregnancy for most women for this reason. It takes a while for the hormones to build up enough for her to have the symptom.
But that is not to say that you aren't pregnant. Everyone is different and they have a unique experience. I would say to wait a full week and if you haven't gotten your period yet, to take another test. Let me know what happens.