Based on the history provided, pregnancy remains a strong possibility despite the negative urine
pregnancy test on 31 January.
With regular 28-day cycles, unprotected intercourse during the fertile window, and a missed period, along with symptoms such as nausea, excessive tiredness, sleepiness, dizziness, loss of appetite, mood changes, and absence of usual premenstrual symptoms, these features are highly suggestive of early pregnancy.
A urine pregnancy test can sometimes be falsely negative if done too early, especially if ovulation occurred later than expected or if the test was not done with early-morning urine.
What is advised:
Repeat a urine pregnancy test after 5–7 days using first-morning urine
OR
Get a blood β-hCG test, which is more sensitive and can confirm pregnancy earlier.
If pregnancy is confirmed, consult a gynecologist for further evaluation and guidance.
If pregnancy tests remain negative and periods do not start within a week, evaluation for hormonal imbalance, stress-related delay, or other causes may be required.
Seek urgent medical care if:
Severe lower abdominal pain
Heavy vaginal bleeding
Persistent vomiting
Fever or worsening weakness
At present, the situation does not appear alarming, and the most appropriate next step is repeat testing or blood β-hCG.