My little girl is also teenie! 2lbs 2oz. Neck 6in, Chest 9 1/2in, length 8-9in. She's 4 1/2 months old!!!
Before I got her I ordered a bunch of XS clothes, but they are HUGE on her. She'll never grow into them
I still use one of the sweaters when we go outside because it's really warm for her (we live in Canada), but her little legs slip right out every time she moves because it's SO big.