How do sentence structure, sentence length, and word choice reflect the maturity of the poem’s speaker in "Oranges"?

The sentence structure in "Oranges" reflects the youth of the speaker in its focus on the speaker himself, which is a common occurrence among the young. Although the speaker's narrative is about his first walk with a girl, he begins seven sentences in the poem with the word "I," and the very final line also begins with "I." The experience is as much about himself as it is about the girl; he seeks to bring meaning to this moment when he is able to purchase a candy for a girl he admires.
The sentence length used in the poem reflects a feeling of being rushed to deliver all the details:

I smiled,Touched her shoulder, and ledHer down the street, acrossA used car lot and a lineOf newly planted trees,Until we were breathingBefore a drugstore.

In this example, the reader can sense the urgency he feels to explain the intoxicating trip en route to the drugstore. He begins his sentence with a simple declarative clause, focusing again on himself, and then notes how "his girl" follows behind, noting all the little details along the way. This one sentence stretches on breathlessly, mirroring the breathless adoration of the young speaker.
The word choice feels familiar and simple. There are no complex ideas, and he doesn't even touch on love. He notices the details that a young person would, such as the "candies / Tiered like bleachers," and says, "I took my girl's hand / In mine for two blocks." The small details here, from considering her "his" girl to noting the exact number of blocks through which they hold hands, conveys that he isn't very mature in areas of romance, and this is a simple and innocent walk.