I started ovulating yesterday night around 10:00pm and me and my boyfriend had sex around 12 midnight and he came in me. possibility if pregnancy?

Around 20%: In any given month that you have unprotected intercourse, your chance of pregnancy is around one in five (20%). If you don't want to get pregnant, you should consider getting on a regular contraception method. You could try plan b also. But it won't help if you are right that you have already ovulated. Sometimes, though, its hard to tell when you ovulate. Best wishes!