It had me wondering what was happening timewise too, for example Baby seemed to suddenly appear on the scene from nowhere.
I am into the last section now and am finding it all hangs together but despite that I am not sure why the book was constructed non-serially in time. It does seem to keep related events of a particular nature together rather than dispersed through the length of the book - well, I think, perhaps maybe

.
I had Adichie's
Purple Hibiscus already, but not yet read, and was wondering about getting some others which took me to the Wikipedia page for her short story collection
The Thing Around Your Neck where I came across this review "She makes storytelling seem as easy as birdsong" (Daily Telegraph).