Anxiety and Depression?

So this is my first post here and unfortunately it's not the best one. I feel like I've been struggling with anxiety since eighth grade (I'm in eleventh now) and depression since last year. I'm saying "feel like" because my parents refuse to take me anywhere to get a mental health evaluation. They say they need to "see more of a reason" to take me. Does anyone know of a way I could go without them knowing, convincing them to take me, or just anything to get through this? I feel like it's gradually getting worse and I'm not sure what to do.