Hi Nikie,
I read your posts and the advice given on the other diary. As that person said, ultimately only you can decide what to do for your birthday.
My plan was to lose for my trip to the US and that would be it. However, CD works so well that I decided to have a 2nd phase and lose more weight. I spent 3 weeks in the US and gained 6.5lbs which, considering the food, the drink, the parties...isn't too bad. Others have gone off CD and managed to gain 10+lbs per week (I really don't know how they did that, because trust me, I enjoyed myself!).
Getting back on is hard cause you know what it's like and you've just had a taste of what you're giving up. But it is do-able. And the people on this forum are here to draw on for support.
You (and your OH) are doing great and, I'm sure, will lose tons more weight before your big birthday. Whatever decision you make then is the right decision for you.
My personal input - I wouldn't want to remember my big party for how beautifully I fit into my frock but couldn't enjoy the party food and drink delights. We've all been to parties where everyone else is having a good time and is well-lubricated and we're not...
Meanwhile, I'm one bar and one soup in, with one (probably) soup to go. I'm cold!!!!!!! Time for a cup of tea!