My period ended around 10/18 give a day or two have sex with man a on 24&28 then had sex with my boyfriend 30&31 and I had a early Ulter sound on 12/1 and it said I was 6 weeks and 2 days and they said I got pg mid oct but I had my period and no sex but they also gave me a due date of 7/24 and the app on my phone says I conceived 10/31 but I keep seen that either that sperm can live in you for 5 days or you don't start ovulating until 12-14 days after you period I need someone to help me understand this

You will need a DNA test to find out considering multiple partners and frequency.