How much difference does one binge make?

After a big binge I'd tend to see a higher number on the scale for the next 2-3 days from bloat/sodium and such, but in the long run it will not make a difference. Don't stress about it! And drinks lots of water.

On the scale, it might make a bit of a difference. If you've been restricting your intake a lot, then there is the simple fact that there will be more food in your system right now, and that has a weight. If you've had extra sodium, chances are you'll be retaining water. If you had extra carbs, they hold onto water too. So, you might be up a bit on the scale.

Have you gained fat? Depends how much you overate by, but probably not. 1 lb of fat takes roughly 3,500 calories over your TDEE (total daily energy expenditure) which is already a number bigger than your daily calorie goal. If you've logged accurately, then you're not even over your calorie goal, so you're still eating at a deficit. (Not sure how accurately you're logging as you seem to have a lot of "quick added calories".) Even if you've gone over your TDEE in this one case, it will likely be compensated for by the amount you've been undereating previously (again, if you're logging accurately).

Do you think maybe if you didn't restrict so much most of the time, you might not feel the need to binge? (Not that I would call having a big dinner a binge). You don't have to starve yourself to lose weight, especially with only 10 kg to lose.

After dieting for awhile, one binge can be good for your loss in the long run! After living on low cal for a bit, your body is going to begin adjusting to that lower intake.... it thinks that is all you have to live on and it tries to learn to hold onto fat on that amount, since that is what our bodies do... hold onto fat to keep us from starving to death.
Giving it more calories now and then, shows the body that we can find and eat more food, which surprises it and keeps it from adjusting to and plateauing at the newer low cal intake.
You might just see more loss because of it. (you can't make it a habit, but every now and then it sure won't hurt! and may help you in the long run)

I overate yesterday too. I weigh every day. My scales were down this morning, not up. Don't kick yourself for breaking your calorie limit once.

I had a massive binge on my anniversary last Monday including lots of cocktails, but I didn't worry about it and just carried on as normal after it and still managed to lose 1lb this week!