My nails and nutrition
It just occurred to me that I am also having this issue. I looked it up and saw that it is one symptom of low thyroid function. Especially for the OP (with a fairly young baby) you might want to get it checked out. (of course, it's also a symptom for other things, including just doing a lot of dishes, lol)
A friend of mine used to have great nails, very thick and opaque. Then she started eating low carb (atkins style, with lots of fat including nuts) and her nails got very thin and brittle. She can't decide what it was from her former diet, which was mostly healthy but lowfat, including whole grains and fruit.
Coconut oil, butter (preferably grass-fed, raw), avocados, raw or soaked and dried nuts, seeds, flax (fresh, because it spoils so easily), extra virgin olive oil, etc. I think the key with fats is to make sure they are as fresh as possible, and to not heat non-heat-stable oils (like olive oil, seed oils, etc.). Low-carb, high-carb, low-fat, high-fat. I think it doesn't really matter so much what you eat, *as long as* you are thriving on it.