Awwwww, so very precious! I knew the xxs ruff ruff would be a good fit.
I love the dress, and the thermals are darling!! She looks so cute!!!
The other little clothes are so cute too!!! Judging from the fit of the xxs ruff ruff, I'd say you'd be safe to order 6/7 inch neck, 10/11 inch chest, and 8 inches in length. It's so hard to order online. Many times the size charts are inaccurate. :/ At her age she probably won't grow more than 1 inch in the neck, girth and length, if that.
Maybe you could sell the larger pieces here, and reorder? Or will she exchange for you?
Some xxs is more like xs. It really depends on the brand. The Wooflink size 1 should fit. But I would suggest going with the tops rather than the dresses. The dresses run a bit longer. Some of the hoodies run a little big too. Ruff ruff couture has several choices, you might be better sticking with that brand.