If it is a new relay it takes at least a week for for the usage to go up, as documented here https://blog.torproject.org/lifecycle-new-relay

You can speedtest your relay to make sure if is working, it uses the command line version of www.speedtest.net. **Don't do this often so not to put any strain on the network!!!**

Do this in one terminal with nyx open in another. For extra fun also have top/htop open and see the CPU increase during the test.

Note the use of exit using torsocks.

About the /home/cache/pip errors. I am sorry, I am not an expert in python / pip, if pip's cache is disabled I guess it means next time you install a python program from pip it will be slow.

Thanks.