who fathers my unborn?

Hello I am still a little iffy on my situation so i went to get a sonogram today and they placed me AT 17 wks and my due date Now could be july 7 or 8 previously when i went for my first scan they told me i was 12 wks and some days and gave me the due date july 1...this is y im confused, I had sex on 9th oF oct (man A/unprotected) had sex oct 12th (man A/unprotected)then i had sex the 15th(man B/protected)and oct 20 i believe(man b/protected) but when i plug in my due date in conception calculators they are saying the 15 of oct is my conception date which i believe would mean MAN B would be the father??? im very confused now because the further they move my days up would indicate man b is the father help me.what do u think