Depression is something that only the experienced can relate to. I find it best to explain what people can do for you (if they want to). It can be as simple as watch a movie with you and not talk. Or sit and listen and not comment. Or let you go with friends and let you simply watch them enjoy themselves without feeling bad that you seem to not enjoy yourself (it helped me to see happy people even though I couldn't be a part of their happiness).

So I guess it's not so much that they don't take you seriously as that they can't relate.

You need a new doctor.