Just a suggestion from someone who's taken much much longer than he expected and stil isn't done. Treat this like you would an assignment from work. Read the requirements, figure out what the "real" requirements are, design your solution, develop and
test according to the plan, document as you go.
This way, if you have to stop for more than a day or so, you don;t have to try and remember what you were doing, or what you had decided to do to solve a problem, etc.
I had to stop after about six weeks and didn't get back to it for several months. I spent the first week or so going over what I had done and trying to figure out what was next. Don't make the same mistake.
Good luck, have fun!
Burk