The speaker lists everything she thinks she isn't: the perfect sister, daughter or friend, the best at cooking, singing, remembering or planning. Then she repeats the same word, "failure," and says she wears it proudly because she was the first to call herself that. It's a strange kind of pride. By naming herself a failure "since day one," before the world could, she seems to be trying to take the sting out of the judgment she expects.
But the pride sounds thin. Her real reason shows up in the middle of the poem: she feels "below" others because she's "not the same." The long run of short lines near the end, where she forgets, talks back, cries, yells and looks tired, reads like a rush of self-criticism she can't stop. The mood is raw and quietly sad. The plain, repetitive language makes it feel like someone convincing herself, and the poem leaves us wondering whether the pride is protection or just pain in disguise.