The most common cause of hair loss is genetic. Male pattern hair loss. You seem to have typical male pattern hair loss and hair tranplant can be a good option for you to regain your hair back. To slow down future hair loss you can start using minoxidil or propecia.
It seems you have seen many doctors and have a treatment regimen. There really isn't much more "out there" in terms of treatment. The best course of action is to find a good doctor and stick with the treatment and follow up with the doctor if the treatment does not work....
Treatment options include drugs like Propecia, to slow down or stop the hair loss, or just shave it off and get scalp micropigmentation which is now becoming an increasingly popular approach for many men that don't want to go through an expensive hair transplants (see web reference below)....
