Welcome to HealthcareMagic. This delaying of periods can be due to PCOS
which you are already suffering from. Other possibility is of course pregnancy
. Most home pregnancy tests
that check urine beta-HCG
are sensitive to 20-25 mIU/ml of HCG. The test can be positive anywhere from about 2-3 days prior to a missed menses to 4-5 days after, but usually it should be done 7-10 days past your missed period. It is not uncommon for women to have negative pregnancy tests when they are pregnant. If the level of hCG is low then you will not return a positive result.
So repeat the tests after 1 week or get serum HCG levels checked which are more sensitive than a urine test.
Hope it helps you. Regards.