Wine, champagne & spirits with diet coke/coke zero are low carb or carb free so that wont have done too much damage, it just puts your fat burning on hold while your body burns the alcohol.
The mushroom soup probably had flour in as a thickener but hopefully not too much. Ice cream was probably the worst thing, as it's 25% sugar and lots of milk but you never know what the quantities were if it was handmade.
I think the most important thing is you had a good time
I've found the weight loss to be the other way around, big losses at first then it slows down to small steady losses as the diet goes on. I do think it has a lot to do with how much you have to lose as well. As you've only got a stone to lose you may find it falls off slower than someone who has 5 stone to lose for example.