Has your GP order any diagnostic test to rule out the possibility of a physical cause? If not maybe you are not being clear enough or maybe being too detailed in your description of your symptoms. I think sometimes when patients are really tuned in and trying to explain exactly what they are experiencing, doctors just stop listening and conclude you are a mental patient.

If you have not had many diagnostic test, I would consider going in an demanding a full and complete physical. Maybe even schedule an appointment with a neurologist to investigate your memory loss issue. They would likely order a CT scan or EEG or something to investigate this. If your GP is just listening to you for 5 minutes, patting you on the back, and handing you an Rx for antidepressants, then I would look for a new GP.