As you have found, there isn't much research on light drinking, however i did read an article that in the early weeks its an "all or nothing effect", ie miscarriage or no effects, i think thats during the first trimester. Sorry can't be more help, but i've not had to give up drinking because i didn't bother with alcohol prepregnancy (mainly due to other health issues).
Try to put the guilt away. If someone told you that there is evidence that drinking alcohol may do damage to the baby in some way, would that reassure you? Of course not. There is no point in scare mongering you as there is nothing you could do now to turn back time. If any damage has been done there is nothing you can do, except worry and punish yourself more and that would not be good for you or your little one. That is why I think it is best to concentrate on staying off the alcohol for the rest of your pregnancy and be positive about the future. The docs have told you the baby appears ok, so go with that and, if you believe in God, pray that the baby is developing as he or she should be and will be born healthy. At least now that you have decided to stop, the baby will not be born cold turkey. I saw a simulated baby born to a mother who drank throughout pregnancy.. The baby was shaking and it's wee eyes looked dead. I cried, it was so horrible. So I am glad you decided to give up now. x
i would like to add to my original comment, my point about the all or nothing is, as you didn't miscarry, it should have had no effect in the early pregnancy. Otherwise, i agree with petal88
I often have a glass of wine when I eat in the evenings - chill out, it's OK! In fact here where I live (Italy - where, to be honest, health and diet is of prime importance), it's actually considered positive to have the occasional glass of wine (particularly red). I went through mental torment too when I was pregnant with my first (I drank more or less what you are drinking) - she is a beautiful, intelligent 4 year old girl now! In fact in the UK (where I'm actaully from), so many people say that you're doing yourself more harm by denying yourself a glass of wine when you really want one than the actual wine itself! Now I'm pregnant with number 2 I am enjoying my glass of wine (most nights) without worrying about it at all - I know it is not going to harm my baby! Don't get screwed up by people who, although profess not to be scare-mongering, say 'let's hope your baby will be ok' (so they actually are!) - it will be - don't worry! Just remember - everything in moderation! What is much much worse is of course things like smoking, and even continuing a very stressful job, or shouting/arguing often, or lifting heavy objects...they certainly do have an effect on the little one growing in you!
So, enjoy the rest of your pregnancy! Don't get hung up about it, please!
they had on the radio yesterday that one or two units a week is actually helpful, apparently it makes baby girls have less emotional problems, and baby boys less hyperactive, but that ws only one recent study.