Problemchild. I sympathise. I found that from week three I was only losing around 1-2 pounds a week. Really annoying. However I made some minor changes which then allowed me to lose 3 pounds (or more) each week.
Those changes were loads more water (3-4 litres), no bars, less salt, no caffeine (it dehydrates) and more packs with more water such as soups and shakes. Also a little extra exercise (in particular walking)has really helped things too.
Just treat each week as an experiment and change one thing at a time until you find what works for you. The water is essential though!