Frustrated mom,
OK, According to her website you should be eating 1484 calories a day. I know you're injured but how about swimming? Do you have access to a pool? An Elliptical would also work. It has almost no stress on your knees. You may also want to incorporate some light weights al well. Work up the pounds when you can. I also think you should only weigh once a week. For Real!! Don't even get near the scale!
Try to pick the same day at the same time of day. I think if you can do that it'll keep you from being discouraged. I hope this helps!!