If you are a constant web surfer, then having a VPN is an absolute most if you want to avoid exposing your private information to third parties. The best way to check if you do have a leak, is to do the following.
Disconnect from any VPN you maybe be currently using, and open this page up again.
Note, which IP address is being indicated when checking your IP
Close your internet browser via which you opened the page
Open up the browser, connect to your VPN and reopen this page
If the IP address you are seeing now is the same one you had before enabling your VPN, then you have a WebRTC leak.