One week probably isn't enough to make a good decision about whether or not your approach is working. My DH, who has degrees in nutrition and exercise science, always reminds me that it might take several weeks (sometimes up to 6!) for a body to settle into a rhythm. Basically, the research agrees with what others have said above.
Also, remember that the body needs a minimum number of calories to simply function throughout the day. If you dip too far below that number, one could hurt oneself in the long run. WW sets their points so that you can lose weight safely. Believe me, they've got you in a calorie deficit! The weight will come off.
This is a marathon, not a sprint.
(I remind myself of this every day.)