Good loss one week, not even a 100g the next?

It's completely normal, and if it bothers you, you are probably better off weighing every 2-4 weeks instead of weekly. Or, get better at looking at the big picture. Last week you lost almost 4 pounds--did what you did really make you "deserve" that big of a loss? I'm guessing the answer is no. Now, you are making up for it. Looking at your average losses, you are averaging right at 2 pounds per week which is on the high side.

I weigh daily and one thing that helps me with the ups and downs is I log my weight on my smartphone app Libra weight tracker. It averages out my numbers and smooths out the highs and lows and gives me my loss rate for the week, 2 weeks, month, 3 months, 6 months and year. It's really quite interesting and it helps to see that, okay, my average loss for the week was 0 but my average for the month is 1.3 lbs per week or whatever it says.