degenerative disc disease is not a disease at all but rather the normal wear and tear on the discs in the spinal column as we age.
It can a normal process and not cause symptoms and it can cause symptoms of pain usually in the lumbar spine or cervical spine.

It's a catch all term that is debated in the medical community and doesn't really have a standard definition.

In your case it sounds like there may be some disc dehydration going on at the C5/C6 vertebrae and may be involved in causing your pain.

Mild retrolisthesis is a vertebrae that is somewhat out of place and can be nothing of concern and can be found in many, many people without any problems.
It may or may not be of any concern for you.

Mild foraminal compromise left greater than right, means that there is some narrowing of the foramen of the C5/C6 vertebrae and may be causing some nerve compression that is causing your pain.

You should really be discussing this with a spinal surgeon for proper evaluation and treatment plan.

Either an orthopedic surgeon that specializes in spines or a neurosurgeon that specializes in spines.

There are conservative treatments to start with that my ease your pain and get you back to functioning again.

Only a spine surgeon can determine what the best course of treatment for you would be.

Good luck and keep us posted.

Fran