One week is really no indication.
Sometimes, because of fluid retention (I assume), I actually weigh more than I did one month prior. My weight jumps around a lot. But if you look at my signature graph you can see that the trend line is moving downwards.
It's the weight loss over time that matters, not your weight on any given day or week or even month. Stick to your plan, but don't be discouraged when your weight stays the same or goes up for a week. More than likely it'll dive down either next week or the week after.
That said, if you see a consistent upwards or stagnant trend for three weeks, I'd take a look over the plan and see if any changes can be made. Maybe the addition of some extra exercise, or a slight reduction in calories. But like I said, I'd wait before doing that.
You're doing great and you should feel good about yourself