Concerned.

I just had my beautiful baby girl two weeks and three days ago. My SO and I just had anal sex and he came in me(from back there). I'm worried for the chance of pregnancy as I've heard you are super fertile after having a baby. I'm not breastfeeding and I'm not sure if any dripped down. I'm still bleeding brown and have been for awhile. What do you guys think my chances are of getting pregnant....? I'm not okay with being pregnant again.....