What is the chance of me getting pregnant?

My husband and I had unprotected sex for the first time, we were under the influence and weren't really thinking it all through. We use condoms for protection against pregnancy and have never had an accident in all 5 years of using them. I don't use birth control, kind of against it, well the dangers and side effects of it. So anyway, my period just ended a few days ago and I have a 24 day cycle usually. What are the chances or pregnancy? We would be welcome to a baby but our plan was to try in about a year when our debt is completely gone. Any advice or websites I can check out would be great Thanks!