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If you are having symptoms suggestive of pregnancy like fatigue, nausea, constipation, increased sleep, hunger and tiredness, mood changes, headaches, back pain, lower abdominal cramps, increased frequency of urine, breast soreness, nipple sensitivity, blue veins on breasts, pelvic discomfort and heaviness, food cravings, dizziness, increase in vaginal discharge without any foul smell or any other associated symptoms like itching, burning rashes etc, then chances of pregnancy is still present.
The urine pregnancy tests can show you false negative test results due to less concentration of pregnancy hormone (HCG) in urine. Visit your gynecologist/obstetrician for examination and tests (blood HCG levels) to confirm/rule out pregnancy. Blood beta HCG levels can detect pregnancy accurately as early as 11 days post conception.
Take care.