Can you get pregnant the day after u stop your period?

I know that sounds crazy... I know i did something stupid. I'm just wondering if it is possible to get pregnant if i just finished my 5 day cycle yesterday? My periods are irregular, i have two conditions that potentially cause infertility, and i am ussually very careful. I love children and would be ok if i got pregnant. I just am not married and my family would be upset with me. They'd still love me, but i am already a disappointment because i got divorced :-/. Anyway we used a condom, but he took it off and i honestly didn't realize until it was to late :-(. I don't think i can so soon, i just didn't know for sure how that works... Thanks for any help.