The speaker keeps hearing dismissive voices: nobody cares about your weekend, nobody wants you here, nobody cares unless you're pretty or dead. Each time, the reply is the same, "but i do." The repetition makes the speaker sound stubborn and a little hurt, as if they are quietly raising a hand while everyone else looks away. By the end of the third line the reply turns into an exclamation, so the frustration is starting to show.
Then the poem shifts from examples to questions. If caring makes you a "nobody," what is the speaker supposed to do with their feelings? The last stanza widens the problem: are we all nobodies for wanting things and having emotions? The speaker also catches a trap in their own anger. Calling closed-minded people "nobodies" would be the same kind of labeling. The mood is confused and vulnerable, but also thoughtful, since the speaker questions their own reaction.