Bipolar Depression

I always knew there was something wrong with me, but never knew what it is. I feel hopeless sometimes and I started self harming. I told my parents, but they basically said it was for attention and I started again a year and a half later and they still are stubborn. I did a lot of research and I know I want help and that's all I've ever wanted for the past 4 years... how could I get checked out and tell my parents to make them understand? I hate to see them heart broken and I just don't know how to basically say, "hey, mom! I want to kill myself!" 😒