Support and advice for a young helpless caregiver?

I am 21 years old. When I was 19 my grandmother suffered a massive stroke which left my mother my legally disabled brother, and myself to care for her. This year I very reluctantly left home for the first time to join an Americorps program that gives me an opportunity to travel, help others, and help obtain some of my future dreams. After being away for a week I rushed home after hearing news that my mother had also suffered a stroke. now my family cares for both her and my grandmother, and it isn't easy. I feel guilty and angry at the fact that I'm 21 and I hardly have time to take care of my hygiene. I get anxious to leave the house because I feel like it's unfair to do anything fun if my family cannot. my mother is losing everything she worked for her whole life because the assistance she gets only covers her mortgage and health insurance costs (she isn't eligible for medicaid/medicare) we can't afford any type of homecare and we are all suffering. To be honest it's too much for me to deal with and i feel like i'm deteriorating in every way possible. I was offered to go back to americorps for the next ten months, and the 21 year old in me knows this is an opportunity i will lose as I grow older and more busy, and also knows that my mom worked hard to give me opportunities. But i can't even leave the house, let alone travel the country without feeling guilty. I already feel like i'm not doing enough. Eventually I'm going to have to choose between myself and my mother who worked herself sick taking care of me. I'm just looking for some advice on the topic. I'm really in need of support.