I am not a psychiatrist and I cannot diagnose you but I can tell you those are all the exact same symptoms I get when I am in a severe depression.

No energy
No motivation
Only want to sleep
No interest in things I am normally interested in
Can't concentrate on things
Screwed up sleep patterns
Changes in appetite
Feeling worthless
Suicidal thoughts
Not living up to peoples expectations and major shame about it.
Can't make it to work
Performance at work goes way down hill.
Totally isolating
Don't want anyone bothering me....leave me alone
Ashamed to reach out for help
etc

Those are all the symptoms I get when in a severe depression and more.