The speaker is caught between fear and desire, and the poem keeps both feelings in view at once. On one side is dread: of growing up, of forgetting, of being truly alone. On the other is a hunger for exactly that solitude. The images of driving with the windows down and playing favourite music make independence sound freeing, even a little romantic.
Midway through, the poem strips everything away. Housemates, neighbours, streets and towns disappear, and the repeated "alone" and "just me" shrink the world down to the speaker's head, body, thoughts and scars. That is where the fear sharpens, because the speaker admits to being scared of themselves.
The ending is quiet and restrained. The speaker doesn't act on the cravings or kill them off, but tucks them in a "back pocket" for the final day. The mood is wistful, uneasy and honest, like someone holding a big wish close and not yet ready to use it.