Big oops

My child will be 7 weeks on Monday. My husband and I had sex today and he came inside me in the heat of the moment. I was SHOOK. I breastfeed but supplement due to supply. I haven’t had a period yet and I’m out of OPKs from our TTC days so I have no idea if I’m ovulating. I had major health problems and dwindled down to next to nothing. Mentally I’m not ready for this again. Plus, I love my girl so much I can’t imagine not giving her all of my attention. What are the chances of pregnancy? I’m so scared of what will happen to my uterus. My OB said wait 18 months and I wanted to wait at least 4 years!