Before a man ejaculates his penis will secrete pre *** and there is enough sperm in that to become pregnant (it only takes one sperm to become pregnant). It also depends on when during your cycle you had sex.
The chances are high if you are ovulating or were about to as sperm can live in a females body anywhere from 5-7 days
I got pregnant when he withdrew, and I was on birth control pills too. If you don't want pregnancy, get yourself on some birth control pills AND make him use a condom. The "pull-out" or withdrawal method is not effective birth control.
There is always a chance... And the pull out method is NOT birth control. You need to be more careful if you aren't ready for a baby. Use some BC