Well, two thoughts here....
One thing the Atkins book mentions as very important is exercise. Are you getting that in? Not a judgment question, as I'm pretty bad about it, but also can see the difference when I do it regularly.

Another thought is that you might want to get your thyroid checked. If it's out of whack, it won't matter how little you eat, your body will hold on to--or gain--weight.

Wishing you the best. Don't give up!