Hi sassypantz,
I normally lurk on here but your story seems so similar to my previous pregnancy I had to come on and add my tuppence worth lol, albeit 3 weeks late!
First of all congrats on your baby news, its wonderful!
I was 1/2 lb under 18 stone when I got pregnant, I felt awful about it but decided to join slimming world at around 15 weeks pregnant. I followed it until around 2 weeks before the birth and went back 5 days after I had my son, I was astonished to find I had gone down to 15st 12lbs, my actual weight during the pregnancy went down to around 17st 3lbs and I pretty much stayed the same all the way through. I did it more for damage limitation raher than to lose weight, I was the heaviest I had ever been and din't want to end up with another few stone post baby. I ate healthily, with the odd craving for cheese on toast satisfied too, had the full support of my midwife and gp.
I felt great all the way through and it gave me a much needed boost once the baby was born. I would thoroughly recommend SW. Hope this helps. Best wishes for a happy and healthy pregnancy.
Clairex