I didn't find out i was prego until 15 weeks. i was binge drinking/moderately drinking that whole time. us says baby is ok. would the us show prob?

No: Fetal alcohol effect reflects a dose related intensity of findings.The original FAS description from France in the 50's came from alcoholics, many of whom died of alcohol related pbs within a year of giving birth.Although no level of alcohol can be considered totally safe, moms have been in your position & had normal outcome.An ultrasound might show some issues, but not all.

The ultrasound: is one piece of information. Consult with your physician further.