It's probably important to realise the long term stuff with Slimming World.
Here's the thing. Diets like Lighter Life, Cambridge and Lipotrim, in my view, are great for fast weight loss... but not all that great at ensuring long term stability. Most of them have some kind of 'maintenance' plan for when you've finished with the shakes etc, but often that doesn't work - as you've experienced.
With Slimming World, you're encouraged to loose weight slowly and permanently. The reason the NHS work with Slimming World is because they've read all the research supporting the fact that Slimming World are better at ensuring LONG-TERM weight loss rather than short term stuff.
It's actually quite stressful for the body to loose weight quickly. I'm not suggesting people should avoid VLCDs all together... but I'm sure most would agree that it's not healthy to do them on-and-off... loose stones and stones and then put it all back on and start all over again.
It is possible to do a VLCD and then come to Slimming World when you've lost most of the weight. Many people have done that successfully and go on to loose in their first week. I don't know if you can face all that milkshake business again... but if you can and you want to be fast, that might be an option for you.
So, yeah, on Slimming World long term you might only loose a couple of pounds a week. You'll be encouraged to eat lots of healthy food and be a little bit naughty every now and again. Like thin people do.
And, when you reach target, you'll be shown how to increase your Healthy Extras in order to maintain your weight... again whilst still being just a little bit naughty every now and again. You'll be encouraged to monitor your weight and as soon as it goes up even just by a few pounds, you'll go straight back on plan and loose it again. Rather than waiting until it's five stone you have to loose, you'll do it at 5lbs. Long term, Slimming World can and does work successfully - there are many on this site who have lost with SW and maintain well. Aside from the odd Cambridge counsellor (and the woman on the Lighter Life advert!), I'm not sure that can be said about VLCDs. Doing a VLCD is great if you can cope with the ketosis side effects, not eating and the cost... but there needs to be some kind of long term plan. Many people come here after VLCDs, because the long term options after a VLCD suggested by Lipotrim, Cambridge etc don't work for them.
But in order to last the long term on SW (cause there's no doubt it does take longer!), you have to acknowledge that you're going to need something sustainable that allows you to live and socialise and be a bit naughty every now and again.
The sad fact is that most diets fail. In the long term, whilst people achieve short term weight loss, most diets don't work keeping the weight off because people go back to their old habits.
It isn't sustainable for you to not eat Healthy Extras or syns at all in the long term - just like it's not sustainable for you to stay on a VLCD like Lighter Life for ever. The downside: it's going to take a while. The upside: if you stick with it and maintain properly, the weight loss will be permanent. You'll learn proper food habits that will enable you to maintain a healthy weight and you will be able to live and be naughty (rarely!) like thin people do.
Good luck with it all,
Ste