I been cramping for the last week but my period havent come yet and the prgnancy test at the doctor said negative but my home ones are positive?

Tests are accurate: Both the home and clinic pregnancy tests are very accurate 3 weeks after sex. In this situation, one can do another home urine test, but of a different brand, a few days later. If the test is again positive, then there is most likely a pregnancy. Sometimes pregnancies fail, and the latter bHCG tests become negative as the bHCG level falls toward zero.