What’s happening to me?!?

Hey Glow community! I just found out I’m pregnant (YAY!) so I’m not even 4 weeks yet. This is my first pregnancy. Does anyone have any insight into why my stomach is already so big? I’ve only gained about 1.6lbs according to the scale and my stomach is usually relatively flat. Any insights!? I’m so happy I’m pregnant and I know my body will be going through major changes but I just didn’t think it’d be that fast..... 🤔🤔🤔 (I have my first doctors appt but it’s not for a couple weeks so wanted some insight before that)