My dad is an Excel freak. He sent me a spreadsheet with a tax table built in and a couple of nifty vlookup routines to help me figure tax rates.
Then I used some algebra to figure out how to calculate what GROSS earnings should be (Before taxes) given a NET (after taxes) amount. That was pretty tricky, but I have it, except for a bug that happens when your gross amount ends up in a different tax bracket than your net amount. But I can plan around that.
So what's the verdict? If I average 25 hours a week from here on out, at my current average hourly rate, I'll meet expenses. I'm not quite there yet, but I feel much more hopeful that I'll get there and then some.