Another consideration when weighing in....weigh at the same time of the day. Personally I gain an average of 5-8 lbs of fluid over the course of the day, sometimes more! Not everyone has a problem with fluid like I do, but it couldn't hurt to weigh consistantly at the same time of day.

I'm with the others. What matters is that you're losing weight and getting healthier. The number doesn't matter all that much. For your purposes, I would use the doctor's scale, but if you want to weigh more frequently, go by yours. Just focus on the change, not the number.