If you put up a picture I could tell you if it is hypoplasia -it sounds like it for sure rather than caries. These are just deciduous teeth though, it won't affect the adult ones and not likely to affect even all the baby ones.
its not just bottle fed babies at risk of rampant /bottle caries -long term breast feeding (ie after the emergence of teeth) can still cause decay as the sugars in bm still wash over the teeth. Some of the worst cases I've seen have been where mothers have breast fed past the age of 2. Actually one of them was a premature baby born to an older mother who I treated when I was a lot younger, he had cavities everywhere but no hypoplasia.