Which pretty much ensures venlafaxine won't work. Whatever benefits you're getting from it probably owe more to the placebo effect than the med.
Antidepressants have no direct effect on anxiety, or depression in the way say aspirin has on a headache. They work by stimulating the growth of
new brain cells (neurogenesis) to replace cells killed, or prevented from growing by high brain stress hormone levels. The therapeutic response is produced by these new cells and the stronger interconnections they forge, not the meds directly. For more detailed explanations see:
Depression and the Birth and Death of Brain Cells (
PDF) and
How antidepressant drugs act.
Venlafaxine has a very short half-life, around 15 hours for the XL extended release version. By taking it ever second day you are probably continually switching neurogenesis on and off and essentially training the brain to stop responding to the med. ADs need to be taken daily.