Parents cheated me (elder daughter) in property matters

We are 2 daughters and 1 son, am the first born. All three of us are married, both sisters in 2004 and my brother in 2007. Daddy was retired government assistant medical officer and he expired in October 2015. Mom is a retired high school HM a year after Dad’s death. When my sister and I were married in 2004, a dowry was promised in property along with some liquid cash. A 3.5L cash was handed over to my parents-in-law a day before my marriage and that was all I am aware of after that. I have never reminded or asked for any other promises that were made as I felt that they would be taken care of at the right time. But unfortunately the time never came and daddy expired also. I never raised any objections when the equal amounts were given to my sister also, and additionally bike and some gold. It’s only at the time of Dad’s burial did I realise that the entire retirement amount daddy received was invested in a land where a multiportions independent house was constructed and was gifted to my brother. Also, liquid cash has been flowing to feed him and his entire family consisting of his wife, 1 son and 1 daughter. My brother basically never worked after his marriage in 2007 and limited his work profile as a “drunkard”. Another multiportions independent house was constructed and are given on rents too and where Brother’s family stay in one double portion of the same building. My sister, who has been staying next street to them with her parents-in-law, along with her husband has been managing all the financial matters of my parents from her home. The own 2 storeys building we spent in as children, some farm lands and plots, I have no clue what happened to all those. I am unaware till date of any other properties purchased as I was excluded in such matters as always. My parents-in-law raised objections but my parents said that they have never made any such promises. It’s very unfortunate how they forgot they spoke to me too. I was too sick to hate anyone due to my treatment for uterus cancer. They haven’t sent me a penny neither visited me. Doctors suggested hysterectomy and then my parents made it very clear that to get my share, I either have to bear my own kid or raise my Brother’s daughter as our own WITH our will written in her name. My husband straight away declined any of their offers. Now, I am 38 and my husband is 43. We both are weak and tired but by god’s grace, bought a single room (1RK) through our mutual hard work in Bhayandar, Mumbai. Realising my Mom’s emotional pressure on us to get this our house as future marriage benefits for my Brother’s daughter (she’s 7 now), we decided we should seek a lawyer to see the possibilities of any shares of mine first. All are Dad’s self acquired properties POA on Mom’s. Unsure if dad left a will or mom made one yet. We neither have strength nor money to invest in fighting for unsure things. Please suggest the possibilities of the options we may have now. Thank you.