If three doctors confirm a diagnosis there's a high likelihood that its the right one. That being said a diagnosis is just a name, if that name gets you the meds that make you feel better then I wouldn't worry about labels as much. Many doctors are starting to say, "We treat symptoms not mental illnesses". Worry about getting rid of the pesky symptoms that cause your life trouble and leave the label to the side to be remembered only when its really important. Also remember its an illness not a definition of who you are as a person. You may have it but you are not it.