Inheritance of father's property

My father was an Officer in a State Govt. Office. He had purchased a land of 1080 Sq.ft in Kolkata. After that he died due to diabetic issues in 1999. He was survived by 1 daughter(myself, then 14 years old), 1 son(my brother, then 19 years old) and wife(our mother). After his death, the money what we got from his PF, gratuity etc, one single storied house was built on that land and we shifted there from our rented house in 2000. My brother was appointed on the same office as a Clerk(permanent post) on compassionate ground and mother was receiving pension since my father's death. I completed my engineering and got job in 2008.After that, our house was increased by two floors with the money contributed by three of us(but nothing was written on paper) in 2010-11. I got married on 2014 and my brother on 2015. Now, in 2016, there is a huge problem between my sister-in-law/ brother and my mother. After my marriage also, I used to give my mother a monthly donation. In May,2016 , as per our mutual decision, my mother used to cook separately and brother & sister-in-law separately. My brother doesn't contribute any financial help towards my mother.The problem again arises from tit-bit issues in August,2016. Now I want to sell the house. What will be the proportions between us? Which laws will be applicable? Any other suggestion.. I will be highly grateful.