coldcomfort I completely understand why you are worried. However, This study makes the point that
Frequency of use [of alcohol] over 9 months of pregnancy also is a necessary condition to produce a child with FASD. Abel (1998) suggested that for FAS to occur, there must be frequent, heavy drinking over the course of the pregnancy and not just a few isolated episodes. Without regular occurrences of heavy drinking (e.g., weekly), then a diagnosable condition within the FASD spectrum is not likely to occur.
Study also points out mothers with FAS affected children commonly underreport the frequency and level of antenatal drinking. It also suggests that problematic drinkers are more at risk from nutritional deficiencies which can cause developmental problems.
I think provided you stop drinking now and makes sure your nutrition is adequate (sure you would!) you are very unlikely to have a pickled embryo.