Alcohol & early pregnancy..?

Samantha
Before I found out I was pregnant I was around 3 weeks I suppose when my fiancé turned 21 and we had been drinking together-- before I found out I was pregnant. I have not told my OB since I'm under 21 and should not have been drinking anyways-- shame on me, yes. I'm just wondering what the chances are that the baby was harmed at that time? I'm currently about 11 weeks. Thanks!