Not to worry MIllie, the scales must have picked up the two bottles of Chardonnay you had over the long weekend.
I've no idea why a fatless drink like alcohol always makes us gain so much weight, it's almost like all acidy drinks open up the fat receptors in our body so we absorb more fat when we eat around that same time.
I say this because on several occasions I've made the personal observation that I've gained lots of weight after having a diet pepsi or an orange juice while I eat. However, if I have those drinks and leave a gap between the meal, I don't gain.
You'll beat the scales next time.