Belinda,
I'm guessing you're not hearing from any of the proofreaders here because that's not how we learned. You've mentioned a background that might indeed be helpful. If you're the type of person who marks up The New York Times for fun, you might have it in you to be a proofreader.
Do be aware, if you pursue this line, that many wannabe writers and publishers seem to think "proofreading" includes all forms of editing. This often needs to be sorted out.
Best,
Michael
