Re: PG and milk is decreasing
9 months is pretty early to start cow milk or soy, IMO. i know the idea of formula sux, but it is less likely to cause an allergic reaction than milk or soy and does have extra stuff to make it nutritionally better for babies. to some extent, too, it depends on if there's any food allergies in your or DH's family. i was a lunatic about waiting to introduce stuff that was a potential allergen because my dad is allergic to *everything* and i didn't want my kids to have to live like that.
if you think it's just a matter of hydration, though, and that she can get her nutrition from solid foods and what breast milk she is getting, then i'd just offer lots and lots of water (add a splash of juice if you need to to get her interested).
fwiw, i tried *everything* to boost my supply, and nothing worked. of course, my DD was about 18 or 19 months when my supply went south, so i wasn't worried about supplementing. but i also know some people who had no dip in supply whatsoever, and many who had a little dip but maintained supply throughout. you know your baby better than anyone, so if your gut is telling you she's not getting enough, then she's probably not.