Stupid question but. Tmi a bit

Shailo🇵🇷 • Mommy of a beautiful baby girl. Doula/CPT
When I got pregnant with my first we had sex the last day of my period. (Tmi but I remember because I had to take off the tampon lmao). Anyway, with my first I got pregnant due to precum so it was a bit rare in it self. So my question is, what are the chances of getting pregnant if you have sex a day after your period ends? My cycles are 26 days and my period usually lasts about 4-5 days 
EDIT: my husband and I don't use any form of BC other than withdrawal, I've been off actual BC since September