Why is the youngest treated like the least important?

The youngest and the least important ?
OK at 14, im not a baby but am constantly treated like one by my mom, dad, older sis (16) and brother (17).
my parents do not try to understand me neither listen to what i have to say. Like last week, they all had a talk about where we should on holiday this summer, when i walked in i was told to go to my room and stay out of the way by my brother, any other parent would have stepped in but oh no my parents just let him boss me around.
I feel like it’s my mom and dad, sis and bro and then me. My siblings- brother particular tease and bully me. My parents don’t seem to care.
How do i make them realise that i am part of the family whether they like it or not and that their actions have to change??

thanks for all answers xxx