doctors scale

I have two scales at home that I use to cross reference my weight and they both say the same thing yet at the doctors office I'm always 8-pounds heavier it's so frustrating since I've been happy to see the number on my scale and working hard at eating better. I'm a plus size girl and use to being on the heavier size (even though my husband is thin and can eat whatever he wants when he wants and not gain a pound it's not fair) I'll a day away from being 32 weeks and measuring ahead so I know weight gain will happen. But this 8 pound jump is bothering me😢