I've got an IP leak checker for you guys who run torrents behind VPNs. Find it at https://ipmagnet.novarata.net/
What this site does is issue you a unique hash in a magnet link. You simply take this magnet link and open it with your torrent client, then go back to the IP Magnet site and look for it to show up.
The website will show you whatever IP is being reported to the torrent swarm, so you'll be able to verify if your VPN client is working correctly with your torrent client.
Remember folks, bittorrent is a tool, and - like any tool - its user decides whether to use it for good or ill.