There are many people who go to EY at the ae of 21,22, even 25 and 30. There’s certainly nothing wrong with it unless you ACT like a “kid” (I guess an girl on seminary age…meaning my age)
I understand you want to be treated as an adult and not looked at as a starry eyes kid straight from high school, as long as you act like an adult, dress like one, no one will think you are a kid. There are plently of people your age who live here.