You might want to check out
Sally Fallon's Baby & Child Care book (link
The Nourishing Traditions Book of Baby and Child Care), in it she has a homemade very healthy formula recipe. I use it on my 5 month old as she needs extra milk that I can't produce. I give her a bottle/day and she loves it! It has a lot of important nutrients in it that commercial formula does not have...and I can't stomach giving my little girl high fructose corn syrup that is in normal (even organic) formula. This recipe includes lactose (that's the sweetener for it), gelatin, sunflower oil, olive oil, coconut oil, fermented cod liver oil, nutritional yeast, milk (raw if you can get it), homemade whey, probiotics (I just use my kefir!), and filtered water. All things that you can order on Amazon or get at a health food store. Even at 1 year, baby's have a very immature immune system and gut, so it's important to give her all the right nutrients. Sally Fallon's book is super helpful and she gives lots of recipes for baby food too.
Having said all of that, kefir shouldn't be a problem for your 1 yr old. The foods that can be problematic at that age are lots of grains (oats, bread, rice), but animal foods and dairy are naturally easy on human's gut system. Her gut is already used to digesting human milk, so as long as she doesn't have a cow's milk allergy, kefir will be great for her. the only thing I would worry about is giving her too much. I don't think that it could replace formula 100%, but it could be an ingredient in her formula.
It's great that you are introducing her to sour tasting fermented foods, she will be much more open to unusual flavors as she grows up. My son (6) loves drinking straight buttermilk because I introduced him to yogurt, kefir, and other fermented foods when he was a baby!
Another great food to give her at this age is homemade bone broth! I have a recipe on my blog, but there's lots of recipes out there. It's super simple to make and will give her lots of minerals and natural collagen/gelatin that makes her gut happy.