This quote below from the article describes much of what I dealt with when I was diagnosed with Major Depression.
Sadness can indicate depression, but the absence of all emotion — including sadness — could also signal depression.
“The absence of key feelings often marks depression, and many people with depression describe their emotional experience as empty, numb, or disconnected,” says Holton.
Numb is exactly the word I would use to describe what I felt. I didn’t look sad, and I didn’t cry. I didn’t talk about my negative emotions. I simply felt nothing. I had lost the ability to feel sad, happy, hopeful, angry, etc. Nothing made any difference, and nothing mattered.
Often we describe depression as sadness, and our media depictions are of people looking and acting sad. We can’t forget that there are also times when depression doesn’t look like that, it might look like numbness, and it might look like anger and irritation.
We’re all different, and there’s no reason to think everyone with depression would feel the same.