One thing is wanting to pursuit your passion, and another thing is getting over that mental barrier to actually follow it all the way. This is easier said than done, as doing this requires abundant levels of confidence as essentially you are blocking all external factors, such as your parents dreams for you, and you are most importantly getting over your biggest enemy - you.
Confidence is Not Gained Overnight
Confidence is a long process, especially if you have to build up large amounts for such a life changing and crucial decision. You have to accept that you won't just earn it overnight, especially if you are someone who already lacks in the confidence department. The best way to build confidence is by doing small tasks that will boost your self-esteem little by little until they become a habit. Doing your bed in the morning, making your own breakfast, taking a shower, organizing your desk, are all small tasks that are often overlooked, but as soon as you do them you feel a small sense of accomplishment that little by little increments your confidence. This tasks will remind you that you are in control of your life and that only you are in charge of your success, allowing for greater strength to make that vital decision when the day comes. The mentality obtained from doing these tasks will make you disregard the external factors I have accentuated so much in the past essays, and will help you defeat the mental barrier you set up yourself in fear of rejection and disapproval from others.
Start with basic tasks and watch your confidence sky rocket.