Hello dear Understand your concern Most common cause of delayed period in sexual active women is pregnancy if you did unprotected sexual intercourse in fertile period of your cycle. Yes tender breast, headaches, always tired, hungry, swings moods are symptoms of pregnancy. You have to repeat the home pregnancy test after 1-2 days in the morning with fresh urine sample. if agian negative then You should go for USG scan and Blood HCG for accurate confirmation of pregnancy. If there will be no pregnancy the you should rule out following causes: Thyroid abnormality, hormonal imbalance, excessive weigh gain and loss, stress, change in life style and eating habit. You should consult the gynecologist and go for following investigations to diagnose above causes in absence of pregnancy: full hormonal assay like aEstreogen, progesterone, FSH, LH, Prolactin, thyroid hormone. Take healthy diet regularly, avoid stress and do regular exercise in the morning, Hope this may help you Best regards Dr. Sagar