The doctor should test for oestrogen in your blood not lack of testosterone. You could be oestrogen dominant due to different reasons
Overweight men produce more oestrogen owing to the extra body fat and the enzyme in fat cells called aromatase. This converts testosterone, leading to a bit of a catch 22.The fatter you are, the more oestrogen you produce and the more oestrogen you produce the fatter you get
Cannabis, amphetamines, alcohol abuse and heavy steroid use are all other factors too.
I would see your GP again and explain how this is affecting yu emotionally