It’s been many, many, many moons since I’ve setup phpmyadmin last, so I might miss something new. However, this 
…doesn’t look right to me. Please provide the output of:
sudo find / -type f -name 'phpmyadmin.conf'
Edit:
Quickly scanning through the instructions, shows me I’m correct:
You seem to have either skipped something, or chopped and changed it so much that it is not obviously where the problem lies.
I recommend starting from scratch and following the instructions to the letter. Not customizing anything to start with, just getting it to work first. And then, and only then changing/customizing as required.