Is Pregnancy Possible Through Intercourse 2 Weeks Postpartum?

Hi I'm 9 weeks postpartum and have mild cramping and nausea. which started 5 weeks postpartum when I had mild spotting for a week. my bleeding stopped 2 weeks postpartum and we had unprotected sex until when I started pill at 4 weeks. I took a pregnancy test today which was negative. .do you think I'm pregnant?