The title doesn't give details about the author and also does not allude to other key themes in the poem, which will be discussed later in this commentary.
The focus of The Author To Her Book is seems to be the narrator's inability to find the writing perfection that he or she seeks. The narrator describes his work as "one unfit for light" (9). The idea of balance seems to elude the narrator at every turn. Every problem solved creates a new problem. The narrator describes how he or she attempted to repair his piece by "washing its face" (13) and "stretching its joints to make thee even feet" (15) yet the narrator still after making repairs "more defects I saw" (13). The focus seems to be the idea of a dead end in which the narrator feels that his piece is in a sense a failure, which needs to be rebuilt as a new body. The author most likely finds the book longwinded as she describes it as her "rambling brat" (8).
In poetry form typically follows function. The fact that the function of this poem is to present one view and perspective: That the narrator views his or her "offspring" as deformed beyond repair means that the form of 1 stanza was a very obvious choice which unifies the statement of the narrator. Unlike poems by Robert Frost who often gave both the positive and negative sides of an argument using the word definitive word "but" this narrator and Bradstreet seem determined to solidify just a single idea. A second or multiple stanzas would have dissolved the unified thought of the narrator.
Although the language of the poem written before 1672 is slightly archaic which use of the words "Thou", "mongst", "didst" etc the language still seems informal. This poem could have easily been read from a mother to her child. The narrator is seems to be speaking directly to the "offspring". Bradstreet might do this to give the reader a general sense of the emotion felt by the narrator during this difficult situation.