I actually have read all of the Columbus' writings, even the "Diary of the first voyage", of which we know thanks to the copy made by Bartolomé de las Casas, although the Dominican friar will occasionally revert from the first person in which they were written to the third person in which Bartolomé tells the Admiral's story. There are also a number of letters to fray Gaspar Gorricio, to his son Diego, to Juana de Torres, and other people.
Some other copies of his writings are to be found in Angelo Trevisan's registry book for his letters, and his copies are perfectly faithful translations to Venetian dialect. Trevisan knew Columbus in the year 1500 and 1501 and they became good friends, that's how he got copies of Columbus' letters to the Monarchs.
Then there is the Libro Copiador, which is a copy of Columbus' own letter registry, made in the XVI century but actually faithful to the original.

I am sorry that I can only provide Spanish and Italian sources, as I read those letters and documents in their original languages. In case of any doubts, I am very glad to help.

Sources:
-DE LAS CASAS, Bartolomé, "Historia de las Indias", MS in the Biblioteca Nacional de España, but there are several editions.

-TREVISAN, Angelo, "Letters", MS in the Library of Congress, digitised.

-Archivo General de Indias, PATRONATO, 295 is the reference for the Archive of the Dukes of Veragua, heirs of Columbus. Digitised in pares.mcu.es

-RUMEU DE ARMAS, Antonio, "El libro copiador de Colón", 1992. Transcription and edition of Columbus' registry book.