My period is two weeks late but I took a pregnancy test which came up negative... twice. What could be going on? Could the test have been wrong? Ive been on birth control for 4 months and never had this problem before. I have not been stressed out of the norm.

Take the pregnancy test in the morning with first morning urine!

Have you changed your diet or lost or gained weight?
All 3 of them will have impact on your period

If you are worried go to the doctor for ablood test