S.G.
I'm kinda in the same boat as you so don't feel alone. I have ostioparosis (sp?) (brittle bones) that runs heavy on my moms side of the family. My dentist told me I have weak enamal on my teeth which could be because of that. I can brush till I'm blue in the face but I still get cavities. Now my daughter is getting her adult teeth in and she is getting brown spots on them. She started getting them on her baby teeth almost a year ago too. She has never had a cavity and goes every 6 months for her checkups. Well I took her to a dentist after we moved here and he said she may have fluorosis (too much floride) but it was too early to tell till she got somemore of her adult teeth in. Well she goes back tomorrow because her upper front teeth look horrid!!! It doesn't seem to bother her yet (kids teasing and what not) but to me it looks like she never brushes her teeth or is a heavey coffee drinker!! So I see what the dentist says tomorrow. From what I've read on the internt, this can't be reversed, only covered up. And I've read that bleaching can and can't be effective.
I just wanted to let you know that you aren't the only one dealing with this and I'll let you know what her dentist says so maybe being ahead of the game with your 2 yr old will help you out!!
S.