Personally I vote Zhure should let you keep it, providing that you supply all relevant rules (thus listing out the races and how the ecl works as per FRCG).
However seeing that this isn't a democracy, Zhure (kinda like Zuul) might just overrule me...
Edit to add; Hmmm, according to FRCG you should only be 3 HD... as you are 3rd level and Tiefling adds no HD (but it does add some spiffy stuff)
If you all need me to I'll post the Teifling as per FRCG, and the ECL stuff...
I think it is well done in here as I played a DwarvenTeifling Monk(crossbreed... the stat bonuses where moved and I had StoneCunning, but only Darkvision 30') in our last campaign, yeah always being a level behind stunk, but laughing at the cold/fire/electricity damage(first 5 points anyway)-Darkvision-and having a once a day save the bacon spell-like ability rocked... (I had animate chain-was a spiked chain weilding monk-like animate rope... the other Teifling had Spider Climb... our DM wanted a little diversity)
Anyway TTFN