What to do

Last menstruatiin is oct 18. supporsed to be nov 18 dpat meron na aq. pero till now delayed pa din. sa flo apps 11days delayed. nagpregnancy test aq nov 21,22,23,24&25, negative. knina nagpregnancy serum test aq negative pa din. Maaga pa kaya for testing? Any suggestion po or may similar case sa akin? ngyn lng po aq nadelayed