Lizzy's poem pictures a girl trapped in a pit, which reads as a stand-in for being trapped inside her own head. In the first half she has no food or water, only her mind, and her one goal is to keep the chaos in it under control. The trouble is that effort backfires: the harder she tries, the more the chaos spreads.
The second half shifts. She now has some food and water, so her body is cared for, but her mind has been "stolen" long ago. The chaos has taken over and claws at her, forcing her to feed it. The speaker sounds exhausted and helpless, and the mood is bleak and claustrophobic, helped by the short, clipped lines.
The ending offers a twist. If she had given the chaos half her mind, she would have kept the other half. The poem suggests that total resistance can cost everything, while some compromise might have saved something. It closes on regret rather than comfort.