I saw that tor has three layers of encryptions and, plus a VPN I set myself on my computer. How can someone trace back to my real IP? Is this completely anonymous?
This setup may, or may not, be completely anonymous, depending on a whole bunch of factors, some extremely subtle. Adding a VPN to Tor basically never improves anonymity, though. Exactly how someone would trace you back to your real IP is in many cases more about how you use Tor, than Tor itself.