Many of the feelings and symptoms you have are from the anxiety that you are going though. The sense of detachment you are having is caused from the rush of adrenaline that is going through your body, it is actually your senses on over drive i.e flight or fight. Since you have followed up with your physician and the results came back fine it is extremely unlikely in my opinion that you have brain damage. My suggestion is you continue to speak with your therapist and if the medicine you are taking is not helping tell him/her that so they can make the right adjustments or changes. I would also consider seeing an psychiatrist if you are not already.