Domino
You may have a hard time finding what you are looking for. I don't recall ever seeing any books that concentrate on Nicholas as Tsarevich for the whole book.
Because in Nicholas's youth, his father, Alexander III was on the throne, most books covering that period cover Alexander.
But you might try some books on Alexander III and even on Alexander II that might have more information on young Nicholas as he was born when Alexander II was on the throne.
You might try The Shadow of the Winter Palace by Edward Crankshaw, although he thinks that Nicholas was a "negative".
Another that might be harder to get is Mother Dear by Poliakoff which is a biography of Empress Marie Feodorovna, but covers the birth of all of her children.
You have undertaken an interesting but very complicated job. Most authors concentrate on Nicholas and Alexandra and the fall of the empire.
There is also Edvard Radzinski's The Last Tsar - The Life and Death of Nicholas II but you have to wary of Radzinski as some of his sources are suspect.
