Hi,
Thought I would add my bit.
I tried to concieve for 10years and 1month and success came when I was at my heaviest. I am quite overweight and have been getting progressivly so over the years with all the stress and depression of long term TTC. I spoke to my most recent FS about it and he didnt seem to have a problem with it at all. As long as you are healthy in everyother way you have just as much chance, if not more, than a thin person. The important thing is no smoking, gentle excercise etc, not just your size. Posistive thinking was my biggest difference with the latest IVF and it was just what the doctor ordered.
Don't be too hard on yourself as you will just add to the problem. I find if you dont worry and stress about losing weight you will find it easier. Instead of thinking you must diet and restrict yourself, just think about what is the healthiest thing to eat when you want to eat. I guarantee you wont gorge yourself on carrot and cellery sticks like you would on hot chips!!!
Good luck with it all.