The huge losses typically occur in people with >60 lbs to lose, not 21.6 lbs to lose. The average loss is up to 1 lb/wk for men and up to 0.5 lbs/week for women closer to goal, so you are doing average or better.

The other thing to think about is that low-carb needs to become a way of life to maintain the weight loss, so it helps to learn ways to make the diet livable.