Can I recover lost work?

The painting I was working on, well.... I messed up. I erased part of the layer I wasn't supposed to and saved it twice before I realized I was on the wrong layer. I lost 9 hours of work. The bak file also reflects my error. I used the undo feature up to its 32 maximum and I still cant go back far enough to fix my mistake or recover the layer before making the mistake. Is there anything I can do? I work on a Mac but I never set up my time machine so.... I cant even try that. Any help would be great if its possible. :(