Unprotected sex is what makes a baby. So yes of course its a possibility.
Well sperm can live inside of you for 5-7 days, so if you ovulate within that week of sex, its still possible. I had sex 2 days before I ovulated and ended up being pregnant.
It depends how long your cycles are. How long do you have between periods? If you have a normal 28 day cycle then you would have ovulated way before yesterday and so there wouldn't be much chance of you getting pregnant. If your cycles are say, 35 days, there could be a chance.