Is it normal to lose this much weight while pregnant?

So today I am seven weeks pregnant I started off with a really high in weight which I’m kind of used to it because I’ve been trying to lose it but I had stopped working out before I got pregnant so I gained a lot of weight.

But ever since I got pregnant I’ve been logging and tracking my weight and over the course of two weeks I’ve been losing a lot of it... But my belly keeps growing...

I started off with almost 170 pounds I am 5’4 and 23 years old and today at seven weeks I weighed 162.4 I have no idea why I have not been exercising but I have adjusted my diet, which I feel like it’s normal to lose one or 2 in 2weeks but not 8 lbs.

I have my first Ultrasound in 2 weeks and I’m wondering if I should wait to let me doctor know or if I should go get checked and make sure everything is okay?