If I'm on birth control and have sex on my ovulation day, could I get pregnant?

Depends. If you have been on BC long enough for your body to respond (weeks) there should not be a problem if you use it correctly. BCPills work by convincing your body you are already pregnant(the hormones), so eggs are not released (saving them for later).If you skip a pill or just started, the body might re;ease an egg and you might be at risk.Otherwise it is quite effective.