You have done so well already - don't think what you've achieved isn't a marvellous achievement because it is!
I would say this - why do you feel you've gone off plan? Is it because you couldn't handle not having certain foods? If so then I can't see how CD would help really, apart from quicker and easier to see results. If you are finding that on SW you want to reach for things that are high in syns or don't work well with the plan or whatever then I imagine those feelings will be even worse on CD. I've not done it myself though. I know CD does work really well, my MIL did it and in no time at all she looked totally different and incredibly thin. I don't see her often as she lives far away so it was like, I saw her and she was her 'normal' self, a couple of months later she was super slim! But then the next time we saw her she had put it back on again and then some and was at her heaviest ever. Now, I'm not saying CD doesn't work, but it's not a quick fix. Believe me, I'd love a quick fix, nice little diet for a couple of months and then back on the red wine, bread and butter but nothing works like that. You are following a great plan and one that is working for you. A few weeks off track enjoying your holiday won't ruin the hard work you've done and you know the principles of the plan so you can eat what you want on holiday but maybe keep the 'red and green' principles in your head, if you're torn between two dishes say that you want equally at the restaurant, go for the 'better' one.
I know what it feels like to have a friend slim really well whilst you don't feel like you are getting anywhere. I did WW alongside my best friend a few years back and I nearly got to my 10% goal and she got to goal! She looked AMAZING and I'd always been the (slightly) slimmer of us so I found it weird suddenly being the bigger one, whilst she got all the attention for how well she'd done. I'd still done well but not AS well and it was disheartening. But you will get there, and healthily too!
Emerald
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