Don't lose heart Flopster - like you, I don't have the dramatic losses experienced by others on the forum. It's easy to focus on the spectacular losses others have but if you looked at what everyone is doing, you'll probably find that most people chug along losing the 'stone a month' average claimed by CD.
Someone suggested making a chart with the number of pounds you need to lose running up the side and, working the time out by averaging the loss at 3.5lb per week (a stone a month) then putting that many weeks along the bottom. Then put a dot every 3.5lb per week and join the line up. THEN chart your actual loss each week. You'll find your loss will run along that line going above it or below it at times but will keep roughly in line nonetheless.
I'm going to do mine today and stick it on the wall so I can see how well I'm doing even on the weeks I feel I've done cr@p (like this week - I only lost 2lb).
In my case, I started with 9st to lose - that should take 9 months (36 weeks) doing the average. So far, I've been on CD for 18 weeks ... 18 x 3.5lb = 63lb and so far I've lost 67lb so although I'm not going to break any CD records, you can see I'm trotting along just ahead of average.
You've been on CD for 4 weeks ... 4 x 3.5lb = 14lb and you've lost 17lb!

See what I mean? Avoid getting bent out of shape over the weekly losses and keep your eye on the average monthly losses instead.
Debbie x