Depression - The Invisible Disease

I'm having some conflicts with work.  I'm about to return from my leave.  My depression is still here, but it's being dealt with.  I'm not going into specifics regarding the conflict, but all in all, I feel that I'm not being taken seriously.  Is there anybody out there with depression who feels that way too?
I mean, I don't have a big fancy scar to show off.... I don't have any broken bones or a body cast.
(I think a body cast would be most appropriate for depression... it pretty much affects your whole body from top to toe....).  It's all on the inside.  I feel like because it's not visible, it leaves people in a state of disbelief, they don't quite grasp the concept that I'm actually sick.  It's frustrating.  What do I have to do, start injuring myself to prove a point?  Is this where people start cutting themselves? So that their problems can be show on the outside and maybe THEN someone will believe that there is a problem? (Don't worry, I won't go that far....)

At first, I had problems grasping it myself, that this actually is a disease. I felt like a phoney in the beginning too, because I didn't feel sick in a way that I'm used to... i.e no fever, no stomach pains (well, nerves but nothing else), no sore throat.... The usual "sick" symptoms were missing. 
It finally sunk in when my doctor sat down, looked me in the eyes and said: "Depression is a serious disease. There is nothing you can do. It's hormonal, it will pass but you're not crazy."
I even broke out in tears in his office at this statement, I guess I realized it myself that I may have suspected that I was a little nutty... or maybe I released some of that guilt I've been feeling for being sick. Or rather for NOT feeling physically sick.... getting the confirmation that "Yes, you are sick" from the doctor was a relief of sorts.

So... is it unrealistic of me to expect others to take it seriously, when it took me this long?  I think yes.... especially in a professional environment where they have my doctor's notes to verify that yes, I'm not well.
Again.... it comes back to no physical injuries. I feel it's unfair.  But hey.  That's life.

I'm dealing with it.