1) Don't major in something just because your mom wants you too. If your head's not in it, you'll most likely end up flunking. Study something you enjoy.
2) Your life is not your mom's life.
3) If being a pilot is your dream and you never pursue it, you will regret it for the rest of your life.
I'm not sure if your mom is paying for your college at all, but it doesn't matter either way. If she is paying part of your tuition, you'd be better off paying your own way to being a pilot than to live off her money and be what she wants you to be. If you go that road, you will be regretting in when you are an old fart engineer wondering what your life could have been had you decided to become a pilot.
If you chose to become a pilot and are successful in that endeavor, your mother has no reason to not be proud of you. If she isn't, then she has problems.
Pursue your dream, not mom's.
HD