Although Daisy's telling us this story years after the fact, her voice reads like she's sharing her unedited stream-of-consciousness with a close friend, with random capitalization to illustrate things she particularly wants to emphasize. For instance:
Dad was one of those Never Mention Her Name Again type of fathers which if you ask me was extremely un-psychologically correct of him. (1.5.10)
The story is told in run-on sentences entirely without quotation marks, mostly without punctuation, and with a lot of made-up words, just like language works inside our heads. Here's another example for your consideration:
[…] the boys […] tried to splash us and then called us to Come In Or Else! and finally we got tired of them teasing so we just thought Why not? and Piper took off all her clothes and I took my jeans off and we tiptoed in holding hands […]. (1.13.11)
It's kind of like we're watching Daisy's thoughts as they roll through her head, which is exactly how we experience the book, if not how books are usually written. While this might take a little getting used to as readers, the upside is that sarcastic asides are frequent in the land of Daisy's brain as well, so when mundane subjects come up, never fear; Daisy's bound to make them a bit more interesting: "I felt a science report coming on titled Electricity, Our Helpful Friend" (1.17.12), she says, and we find ourselves chuckling about lights for the first time ever.