The analyses of a text #2

The narrator recalls his adolescence.
He is an apprentice for the lawyer Mr. Spenlow.
He is crazy for Mr. Spenlow's only daughter Dora.
His grand aunt and her distant relative Mr. Dick came to London after her going bankrupt.
Now, He works as the secretary for Doctor Strong in his spare time, who was the head master of the school the protagonist went to.

My new life had lasted for more than a week, and I was stronger than ever in those tremendous practical resolutions that I felt the crisis required. I continued to walk extremely fast, and to have a general idea that I was getting on. I made it a rule to take as much out of myself as I possibly could, in my way of doing everything to which I applied my energies. I made a perfect victim of myself. I even entertained some idea of putting myself on a vegetable diet, vaguely conceiving that, in becoming a graminivorous animal, I should sacrifice to Dora.
As yet, little Dora was quite unconscious of my desperate firmness, otherwise than as my letters darkly shadowed it forth. But another Saturday came, and on that Saturday evening she was to be at Miss Mills's; and when Mr. Mills had gone to his whist-club (telegraphed to me in the street, by a bird-cage in the drawing-room middle window), I was to go there to tea.
[David Copperfield by Charles Dickens]
1. I'd like to know if "myself" is implied after "sacrifice."
2. And I'd like to know the difference between "otherwise than as," and "otherwise than" here.
Thank you in advance for your help.