I havent heard of the concept of "major" and "minor" in latin american universities, at least its no common as in the US and other countries. So all we have is a "major" that we call "carrera",
so you can say: Tengo una carrera en estudios de la lengua española. or
Mi carrera es en estudios de la lengua española.
("Estudios de la lengua española"is the name that universities commonly use to refer to the spanish language studies)
or you can say : Tengo una especialidad en estudios de la lengua española.
I hope this helps :)
Saludos