Just an FYI. There is a bunch of bone (the spinous processes) and gristle above the spinal cord. ('specially near thewithers) This is why arrows hitting here rarely blow through.

It's a meat hit.

Usually an arrow hitting here will have more fat and meat on it than blood. Blood sign is usually sparse at best. If there is a blood trail it usually quits after about 200 yards.

Waiting was the right thing to do. But the deer is likely still running around.