How can I prove from the text that Jane Austen's Pride and Prejudice is totally Victorian with "very little Romanticism"?
To assert that Austen's Pride and Prejudice is "totally Victorian" with "very little" Romanticism is difficult to do for several reasons, primarily that the novel was written by 1797, though not published till 1813, while Victoria's coronation initiated the Victorian Age in 1837. Victorianism in literature was a phenomenon of the late 1800s, not earlier. Another reason is that Austen's novel does bear characteristics of the Romantic period, though in a more subdued expression from other Romantic writers.
One characteristic of Romanticism is that passions (emotions) are recognized as governing human behavior along with reason, formerly considered the highest hierarchical power. Victorianism adds moral responsibility as a governing passion, thus writers challenge and expose social ills while striving to motivate corrections to urban injustices. Austen's novel focuses on the feelings and exertions of the will--the passions--of her characters, as, for example, with Lydia. That Lydia is governed by her emotions is fairly obvious from the way she follows the Regiment and forces Wickham to take her with him in their escape to London. That she exerts her will above employing rational reasoning powers is also obvious from her assertion to Darcy that she doesn't much care whether she is married or not:
[Darcy] found Lydia absolutely resolved on remaining where she was. She cared for none of her friends; she wanted no help of his; she would not hear of leaving Wickham. She was sure they should be married some time or other, and it did not much signify when.
Another characteristic of Romanticism is that literature focused upon a select few characters in well defined scenarios, whether poetic, like Wordsworth's The Ruined Cottage, or prose, like Austen's Pride and Prejudice. In contrast, Victorian novels were peopled with many, many characters in complex situations with multiple complications that were heavily plotted in long novels that showed urban life realistically. Austen's novel is elegant in its choice of a select few characters who reveal the psychology behind behavior in typical social situations. For instance, Austen's novel doesn't delve into what might be seen as economic injustice toward the workers on Lady de Borough's estate; instead Austen shows the psychological dynamic at work in how Lady de Borough relates to those workers.
Having said this, there are a few points that might be extrapolated to show the similarities to Victorianism. Though the idea of the sublime--that which invokes emotional sentiment but which is not in keeping with Classical ideals of beauty--is an important concept in Romanticism, it is largely missing from this novel. The trip to the north country, originally planned for the Lakes, is the only introduction of the power of nature, which was of such importance to Romantics. However, Austen uses no symbolism that draws upon emblems taken from nature, another important tenet of Romanticism.
There is no self-sacrificial love--one of the earliest principles of Romanticism derived from Goethe's original Romantic work The Sorrows of Young Werther. Austen does use this in Sense and Sensibilityy though absent here. Finally, Austen's ironic narrator heralds the Victorian Age because the tone of irony and wit was critical to works by authors like Dickens who sought to make the social plight of the downtrodden a national issue of reform.