Can I be?

Is it possible to be pregnant 5 weeks pp?

Im only breastfeeding & I know that's not any form of birth control or anything but I heard that you're less likely to get pregnant when you're only breastfeeding, im not sure if I've gotten my period or not.. but me and my husband have been having sex without protection and I've been wondering if there is anyone that has gotten pregnant so soon after giving birth? Is it possible...?

I took a pregnancy test (I know it may be to soon) it came out negative I'll be taking one in a few weeks again just to make sure .