From using Fitday I've learned that certain foods cause me to stall or gain even though I'm eating 1200 calories a day. Check over your food list to see if there's something new you added when the weight gain started happening. My problems are grains & starchy food, but yours could be something else. I read somewhere here about a person who experienced this when eating artificial sweeteners. It's so frustrating, I feel your pain. Just don't give up - you can make this happen.
"Most folks are about as happy as
they make up their minds to be."
- Abraham Lincoln