If you just graduated highschool, and you have this dilemma, then your future is NOT going to be anything related to the piano unless you want to teach it. If you go to a university/conservatory for music, your future will NOT be in playing the piano, unless you want to teach it. If you have not participated in at least small piano competitions and easily won them, your future will NOT be in playing the piano, unless you want to teach it.
If you think music is your life, then you have no future in music. It's pretty bleak but that is reality. Music is a very narrow field of study, those who only have their hearts and souls firmly planted in it have no hope for growth as it is a highly energy intensive endeavor. It is also one that is surrounded by many other related aspects that most musicians are not aware of. This ignorance reeks from many conservatory/university music students and in the short term, a couple of years, you'll realize that you just wasted your time, money, and energy on a hopeless pursuit.
Unless you plan on teaching it, listen to your mother. If you do plan on teaching it, be the most effective teacher you can be because it is obvious that there is a need for better piano teachers.