Hi,
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Your symptoms (delayed periods, sore breasts, nausea, abdominal discomfort, bodypain, tiredness) could be suggestive of pregnancy. Urine pregnancy tests can show you false negative results during early pregnancy days. It is because urine pregnancy test kits are calibrated ones, so they show positive results only after the hormonal levels in urine have reached a certain level. Blood HCG level estimation is accurate and can detect pregnancy accurately earlier than urine pregnancy tests (at about 11 days post conception). Consider visiting your gynecologist/doctor for a thorough examination (to confirm pregnancy related changes/signs in body) and a blood/serum HCG level test (to confirm/rule out pregnancy accurately).
Take care.