Clothing for small baby’s

Tanisha

I’m from the uk and the sizing basically goes

Newborn: up to 6lb

First size: up to 9lb

And onwards basically! But they’re currently saying my little girl isn’t very big, her sister was only 6.14lb so would I buy both sizes just to be safe or just newborn?

When her sister was born they told me she was gonna be 8lb but she was a little doll and her clothes didn’t fit her at all 😂 So I don’t wanna mess up this time around