Since her parents sent her to a Catholic school that taught OP to be unassertive and have poor boundaries it is very possible they share this approach, and her father’s response suggests this.
OP is well old enough to deal directly with Barn Manager and trainer without a Mama Bear in her corner.
Also parents responses can be very unpredictable on a scale of dismissal to over reacting or blaming child. It doesn’t sound like a home environment where she will get optimum support and advice.