Sex before period returns

Sooo I am getting anxious. I stopped bleeding last week got really excited so my husband and I had sex he pulled out...well we’ve had sex a few times since then and he hasn’t. What happens if you get pregnant before your period comes back? How screwy will it be as far as figuring out due date? My doctor said we needed to wait basically to get a good due date down 😬 I guess I’d prefer my period to come before I get pregnant again but also would love to be pregnant sooo idk 🤦🏻‍♀️