Welcome to the forum There really isn’t anything to be scared about, she weighs 9lbs and even though that’s on the smaller side for her age it isn’t crazy small. I just had a 6lb puppy leave at 8.5 weeks old and she is thriving. If you haven’t already, follow up with your vet, make sure she is dewormed and feed her a good quality puppy food. The issue many have is that they over feed as they want them to grow faster. That’s not how that works. Feed her the appropriate amount for her size. I’m thinking the round belly is because she needs to be dewormed.