The speaker of "under the covers" feels unsafe everywhere: in the town, at both parents' homes, even in any bed they could call their own. The repeated line "and it's because i don't feel safe" works like a refrain, as if the speaker keeps returning to the same fear and explaining their behavior through it. Hiding in oversized clothes, lying awake, keeping their mouth from opening wide, and wanting to bite all read as ways of protecting themselves.
The poem then turns inward. The speaker wonders whether the anger and pity of others might be their own fault, and agrees they might be pitiful. The last two lines are the darkest. They suggest self-harm and the idea that someone else has always "finish[ed] the job" for them, which hints at harm done by other people, though the poem never says exactly what happened. The mood is raw, exhausted, and quietly bitter. The flat, lowercase voice makes the pain feel even heavier.