Unprotected sex please help!

Okay so I have a problem. I was on birth control for a while and my husband and I decided we were going to do natural family planning and just count my fertile days. I completed the whole birth control pack. I was supposed to start a new pack on Wednesday and I didn't not. We had unprotected sex 3 days before not thinking it would matter. But I have had light light cramping and experienced cervical fluid the following Tuesday and Wednesday after unprotected sex. Could I have ovulated and gotten pregnant that fast?? Help!!