Daughter Supporting Family with Interest Money

Assalmualikum. I am a female living with my mother and siblings. I work as a freelancer and have some savings in my bank account. I know interest is prohibited, but my brother doesn't support us. He never worked 3 years after my father's death, and now he works but spends all his money on himself. I deposited my savings in a bank account, and my mothers and sisters used that money. I live with them, but in order to save myself from that money, I give some extra money from my own earnings, like an amount sufficient for one person's expenses. Am I safe? or am I obliged to bear the costs of my sisters and mother. The interest money is enough for them to run the house, and my brother lives off of that money too.