20 weeks pregnant and losing weight?

i’m turning 20 weeks in a couple of days and I weighed myself before I doctors appointment a few days ago and I noticed I lost 7 pounds of pre-pregnancy weight

is that normal? my doctor said it was but she didn’t look so sure and i’m worried. the ultrasound and bloodwork showed everything as fine and baby boy is healthy. i’ve been trying to eat as much and as healthy as I can but there are days i have nausea and days i have no appetite and days I can’t stand anything

anyone went through the same?

how did you gain weight and what helps?