What kind of soy milk ar eyou using? Many brands have alot of added sugars, wheat and other nasty things. I use unsweetened or soy slender which have no added ingredients which add carbs.

It could also have to do with your time of month. Are you having alot of salty or processed foods that could cause you to retain water? Are you making sure to avoid all sugar free candies and protien bars? Why not post some of your menus here so people can better help?

It also helps to rememebr that weight loss isn't always constant. Most in thier third week notice a slow down while thier body stopps and catches it's breath. After that the loss continues, in a slower healthy rate. For many it also comes in batches with a little stall or gain just before a loss.