Wouldn't advise turning off ipv6. We are probably getting near the point where some public services will disable or offer v4 as only best effort, and when this happens, your connectivity will be broken for certain things if you disable v6. Heck, it's to the point now where all my home hosted services are v6 only.
The better solution is to just get a VPN that supports ipv6 like airvpn or mullvad. I think pia disables ipv6 while the tunnel is up, which is better than disabling ipv6 altogether.
To validate the tunnel is working properly you can use something like this.
https://ipleak.net/
There is also a Torrent Address detection section, that when you activate it, will provide a magnet link that will show your ip to ensure that it is tunneled properly.