Hello, A single tablet does not usually postpone menstruation to such an extent. If you are sexually active, you should test for pregnancy using a home pregnancy test and a sample of fresh early morning urine collection. You can also get an estimation of serum beta-hCG titres for a better and an earlier confirmation. These can be done or after waiting for a couple more days to see if you get the period. If you cannot still see a period after the tests rule out pregnancy, see a specialist for further help. Take care.