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The possible symptoms that are common in pregnancy include - Missed periods, Breast tenderness, Nausea in the early morning, Vaginal discharge from pinkish white to brownish, Spotting, Fatigue and Increased urge to urinate.
In your case, though the history and your symptoms mentioned do indicate your chances of pregnancy are high, it can be confirmed only by a home pregnancy test done after you miss your period.
Other causes of breast engorgement and tenderness can be due to overstimulation during sexual intercourse and or mastitis (inflammation of breast tissue).
In your case, if the breast pain is very severe and there is redness over lying the breast, you should consult with a doctor for proper advice and treatment.
I hope this helps.