How can I convince my parents to accept my marriage to a handicapped girl in an Islamic way?

Assalamu alaikkum, I want to marry a girl(Fathima) who is handicapped. She doesn’t have both of her legs. We both wants to marry each other. But my parents are strongly against this decision. My parents think that we will not be able to deliver children if we marry. My parents also think that they may need to put extra hard work to take care of Fathima after marriage. So, they are totally against our decision. But myself and Fathima have taken up the decision to marry. We have also decided that parent’s permission is essential for our marriage. Since i am the only one taking care of my parents, i cannot afford to leave my parents. My parents and Fathima, both are inevitable for my life. InshAllah please advice how to convince my parents in islamic view point. What should i do now? JazakAllah was salam