However, we live in the garage above her father's house. She comes home and literally drops everything wherever. She's lazy, irresponsible, and won't listen. I know the easy answer is to move out, but I find it so difficult to pick up and move. I also feel like it's her that should have to go through the trouble of moving.
Roommates can find a way to get along if they want to get along.
It's actually that simple. You can bitch and moan until she's 39, but don't expect things to change. Considering it's her dad's garage, you might want to begin to explore your options. I suggest one last very serious conversation. Either she changes her ways or you change your address.