Don't worry you'll keep on losing, I lost about the same my first 4 weeks, now at 3 months I'm down 60 pounds. Some of us lose slower than others but we DO lose. Actually I'm hoping this means I'll have less loose skin since it's having time to adjust to my weight loss. I've never lost 60 pounds in 3 months before either or known it would stay off if I relerned how to eat.
Hang in there, it does work & weighing once a week is plenty, you won't lose every day.