How do I ask for a raise?

I am the only social worker left. I have double the case load. I am getting no supervision that I was promised. I barely can take lunch breaks. I received the mandated booster shot before it became un mandated. I need a raise but am not sure how to ask for it / what is a normal amount to ask for? I know the salary of the previous 2 social workers but they had each other to Split the case load and received supervision. Should I ask for more?