If the gang are right about you mixing your vocals with pre-mastered stereo backing tracks, then a few hints.
First, don't JUST reduce the level by 12dB (though that's a great start). Actively mix your voice against the track using whatever form of automation or volume envelopes your DAW offers.
Second, if the back track is heavily compressed as they often are, use a similar amount of compression on your voice.
Third, give a good listen to your backing tracks and, if they use things like reverb, try to emulate that effect on your voice so you sound like you were in the same place.
Finally, you can often make your voice stand out better by doing some light EQ to knock down the levels just a touch in your vocal range...you'll have to work out what suits you best but we're likely talking something like 3 or 4dB cut between 200 and 800Hz. This can make your vocal sit better with the backing.