Continue calling your “middle name” your “middle name”.

P.S. Your “first name” is also known as your Christian name.

hERE is more info about middle names. (Like anyone cares).

Despite their relatively long existence in the Western world, the phrase “middle name” was not recorded until 1835 in “Harvardiana,” a periodical of the time. Since 1905, “middle name” gained a figurative connotation meaning a notable or outstanding attribute of a person. This figurative use is especially popular in films.

The use of multiple middle names has been somewhat impeded recently by the increased use of computer databases that allow for only a single middle name or more commonly a middle initial in strong personal records, effectively depriving persons with multiple middle names of the ability to be listed in such databases under their full name. Especially in the case of government records and other databases that are used for legal purposes, this phenomenon has sometimes been criticized as a form of discrimination against people who carry multiple middle names for cultural or religious reasons.

In the United States, the middle initial is sometimes used in place of the middle name on identity documents, passports, driver licenses, social security cards, university diplomas, and other official documents. Examples of this form include George W. Bush and John D. Rockefeller.

Much more rare is the practice of using the middle name instead of the first forename for everyday interactions. This is often referred to as “being known by the middle name” or “going by the middle name.” (See List of people known by “middle” name.)

In movies, the middle name is sometimes used to express a certain character trait. For example, a character who is about to enter a dangerous situation might say, “Danger is my middle name.” This has been used to much that it has come to be regarded as a cliché.

interesting question though