Birth Control and Unprotected Sex

I lost my virginity 3 days ago and I have been on birth control (Minastrin 24 Fe) for about 2 months. We did not use a condom but he said he pulled out. I know this is not effective. I am very good about taking my pill but I am still so nervous I'm pregnant. I know I'm probably just paranoid, everytime I think about it my stomach feels weird. Help!