Well i NEVER drank in my 2WW's for 7mths while ttc but in our last cycle before the BFP we went to a wedding and i was in my 2WW but only was going to have 2 or 3 drinks but ended up having quite a few more than that and the next day had the urge to pee on a stick and well, well a BFP!!! I was only 3wks4days pg so very early stages anyway....
I had almost given up ttc and wasnt thinking about it much that last 2 weeks anyway i think that really helped!!!

I think you'll be fine to have a few drinks. If it's meant to be, it's meant to be remember that

Like someone else said, once you are about 6wks pg onwards i think that's quite a crucial stage of development for the feotus.