My period is a week late, I was on antibiotics about 2 or 3 weeks ago, and me and my boyfriend have sex with a condom and it never broke or had rips or tears in it. Could I be pregnant?

It's possible. Was the condom used correctly? Put on before any penetration at all? Have you tried a pregnancy test?

It could be your period is just off. Try a pregnancy test... following the directions exactly. If negative, give it another week and see if your period shows up late. If still no period, wait until next month and see if your period shows. If not, try another test at that time or see your doctor.