Tapering, particularly using benzos, rarely if ever works in an outpatient situation if one is drinking as much as a 5th a day. Xanax is very short acting and somewhat euphoric, so it's rarely used to ease withdrawals. Longer acting benzos are far more common, particularly valium or librium.
I realize that you are under a doctor's care, but I would suggest a doctor is a psychiatrist who specializes with addiction.