I felt like this on my AAM week, when I actually got weighed I'd only lost 2lbs which in all honesty I was disappointed with. I lost 3lbs the next week and 5lbs this week. Try and look at your loss over a monthly period, the bigger losses should balance out the odd disappointing week and average out to about a stone a month.
Congratulations on your fantastic loss so far!
Corinne x