Advantages of Pieces
Creating disconnected pieces isn't necessarily bad; it can have advantages too.
Putting the Pieces Where They Belong
Deviations in microchronology are almost always errors (suboptimal choices) – there might be some good reason for presenting two events out of order, but I cannot think of it. Deviations in macrochronology are different. One of the strengths of a book is being able to move back and forth in time, and there are a lot of ways this can be used effectively.
Here, there is a simple and obvious advantage to telling the past as disconnected pieces: The event of the past can be placed where it makes the most sense. For example, my four flashbacks were inserted where she was learning something she would then use in the story.
Avoiding Gaps in Time
Even if a story is in perfect chronological order, there will always be jumps forward in time, skipping over times that are boring and irrelevant to the story. For example:
After two more days of walking, they crested a hill.
Those are not a great trouble, and readers are used to them because they are unavoidable. But they can't be too good either, because they aren't natural.
And large jumps can be unnatural. One book begins the second section "1985". A jump forward? Presumably, but how far? I had to search for the heading for the first section to know. It was a few years into the future, so it was a big jump to make.
Anyway, when events are relegated to the past, there is no need to address the gaps between them. That can be a convenience.
For example, my character has a bad leg, caused by an accident in seventh grade. That event is in the timeline; it eventually gets told. But if I started my book at that point, there would be a jump from that time to 12th grade. (Meanwhile, I put the desription of this in dialogue, so there was no jump backward.)