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You can get a negative test even if you are pregnant (false negative result). Look out for other symptoms suggestive of early pregnancy like fatigue, constipation or diarrhea, increased sleep, hunger and tiredness, mood changes, headaches, low back pain, lower abdominal cramps, increased frequency of urination, 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.
Visit your gynecologist/doctor for examination to look for early signs of pregnancy (breast, uterus, vaginal and cervix changes), and blood HCG level tests to confirm pregnancy.
Take care.