How can one deal with intense and unwanted attachment to a doctor who treats the questioner like a daughter, especially since the questioner has lost her parents and yearns for affection? Is this attachment considered pathological, and what is the way to deal with it?

This is a trial from Allah, so be patient and seek reward from Him. You should increase your remembrance of Allah and your obedience to Him, maintain your prayers, and avoid sins, for these are among the greatest means of healing from psychological and other illnesses. You might be mistaken in what you imagine about the harshness of your maternal uncle and aunt; perhaps it was for the purpose of reforming you. There is no harm in seeing a psychiatrist, provided you adhere to the rules of interaction with them: it is not permissible to be alone with them or to look at them with lust. If you cannot comply with this, then seek a female doctor.