Hey, your father just got a full time job! So what's going to be their problem? She gets SSDl, which I know isn't always a whole lot, but it helps! I'm also on disability, along with a pension, and I'm supporting 3 people on it.
You should NOT feel guilty about moving out. You don't OWE your parents anything!!! They brought you into this world, and whatever they did for you, they were SUPPOSED TO. Now it's YOUR turn at life. For heavens sakes, you haven't even HAD a life yet, and you're 27. You've been taking care of THEM. That's above and beyond the call of duty.
Get rid of that guilt!!! Move out, and have fun and enjoy yourself. It's about time! And you don't have to help your parents anymore! There are social agencies for them if they need help. Let them take care of it.
But for you -- it's YOUR turn to fly. Spread your wings and do it! God bless you and please take care. And throw that guilt away. Hugs, Lee