Sex postpartum and pregnancy.

This is a bit long and probably won't make sense since I can barely make sense of it, too.

My husband and I finally had sex 2 days ago (5 weeks pp) but it was in the heat of the moment since we had gotten in an awful argument and then ended up having makeup sex. I wanted to wait til after my pp appt so i could get on BC but we fucked it up. We were stupid about it since we didn't use any protection. You'd think we learned not to do that after having our son lol

I AM SO WORRIED THAT I COULD BE PREGNANT. I haven't gotten my period and I am breastfeeding so i've heard that stops you from conceiving, BUT i also know women who've gotten pregnant either way. When would I even test to make sure I'm not pregnant? I have my postpartum appt tomorrow. Could my OB be able to help me figure out if I'm pregnant this early? I know she's gonna shame me for it, though. We wanted to have another baby, but not this soon!! I can't believe we were this dumb.