thanks for posting this and coming forward to share your situation.
I read your post thoroughly, and I can envision your situation. I can imagine to a great extent how the whole situation must be affecting or making you feel. However, I also know that only you could actually feel how you must be feeling.
I am not going to tell you to do anything here which would make you stop caring. Your post here shows you have concern for your own self. It shows you have not been able to feel the way you would want to feel like. And the environment at home and the treatment from your family members, which you experience, is not letting you feel the same. The unfair and partial behavior and treatment from your family members is something you, or maybe anyone else, could hardly ignore or not care.
So, I will tell you just one thing. We human beings can sustain, survive and even thrive in even the worst of environments if we want. As I, or perhaps anyone else, might not come to you and help you change the structure of your family situation, or make your family members understand or put some sense in them. However, what we can do, or what any other person in your life - perhaps outside the family - can do is provide you with enough support, encouragement, guidance, steps, tips, to help you function in the very same environment. Help you gain control of your emotions to feel the way you want to feel. Yes, indeed that is possible!
Also, I am deliberately not touching the patriarchal family system in South-East Asian countries (although I actually know about India only).
You have been really brave to be able to sustain that environment and even braver to seek out guidance with your post here. So, do not stop now. You are moving in the right direction. Take one step further, and speak with a couple of experts here. And I am sure you would find a whole another side of your personality to come out a champion and even possibly outshine your brothers. Because you can.
All the very best!