....
For the people who are reading now, that hasnt 2fa on, I recommend you to do so, as soon as possible.
and if you will lose device or reinstall app which you use for 2fa you will lose and bittrex account )
look at the reviews and feedback about Google Authenticator
I lost the device where I had 2FA, I wrote Bittrex support, I was waiting for the 2FA cancellation week and the problem was resolved.