Hindi is the language, and devanagari is its script.
Viki lists languages, not scripts. Because each script can be used for many languages. For instance in the list you will find “English”, “French”, “Italian”, “Spanish” and so on, but not “Latin script” (because that script is used for many languages and it would be confusing).
The Devanagari script (देवनागरी, romanized: Devanāgarī) is the official script of Bodo, Dogri, Hindi, Konkani, Maithili, Marathi, Nepali, Sanskrit, Santali[b] and Sindhi[c] languages, 10 of the 22 official languages of the Indian Republic, and also of Nepal. It was developed and in regular use by the 7th century CE and achieved its modern form by 1000 CE. The Devanāgari script, composed of 48 primary characters, including 14 vowels and 34 consonants, is the fourth most widely adopted writing system in the world, being used for over 120 languages.
The orthography of this script reflects the pronunciation of the language.
The Constitution of India says:
The official language of the Union shall be Hindi in Devanagari script. The form of numerals to be used for the official purposes of the Union shall be the international form of Indian numerals.
— Part XVII of the Indian Constitution[18]
Being the official script for Hindi, Devanagari is officially used in the Union Government of India as well as several Indian states where Hindi is recognised as their official language, Bihar, Chhattisgarh, Haryana, Himachal Pradesh, Jharkhand, Madhya Pradesh, Mizoram, Rajasthan, Uttar Pradesh and Uttarakhand, and the Indian union territories of Delhi, Andaman and Nicobar Islands and Dadra and Nagar Haveli and Daman and Diu. Gujarat and West Bengal also officially uses Devanagari as these 2 states recognises Hindi as their additional official languages.
So what other script would you be using, if not that?
Or do you mean that you would write Hindi using the Latin alphabet? LOL.
Latin script
The Latin script (or Roman script) is the sole official script for English language (Indian English), one of the official languages of the Union Government of India as well as many states and union territories of India.
Indian English is a group of English dialects spoken in the Republic of India and among the Indian diaspora. English is used by the Indian government for communication, along with Modern Standard Hindi, as enshrined in the Constitution of India. English is also an official language in seven states and seven union territories of India, and the additional official language in seven other states and one union territory. Furthermore, English is the sole official language of the Indian Judiciary, unless the state governor or legislature mandates the use of a regional language, or if the President of India has given approval for the use of regional languages in courts.
In short: In India, Devanagari script is for Hindi (and many other Indian languages) while Latin script is only for English.
You’ve been learning the language since the age of 13 and you didn’t know that? (Unless 13 is not such a long ago for you)