It is possible to still be pregnant even if multiple pregnancy tests come back negative. Factors such as stress, intense physical activity, and recent weight loss can cause a delay in menstruation. It is recommended to wait 3 weeks after unprotected sexual intercourse during ovulation to take a pregnancy test for accurate results. It is important to use a reliable pregnancy test from a pharmacy and to test with the first urine of the morning. If you experience symptoms such as fever, difficulty urinating, or a constant feeling of needing to urinate, it is important to consult a healthcare professional for further evaluation.