Who is the father?

Patient: Okay im pregnant and concerned who is the dad. i had sex with 3 guys!Guy Number 1 we had sex on may 18 then may 27 i had sex with Guy number 2.my period came on the 28th of may and lasted 3 to 4 days like normal!.but then i started spotting a day after my period or did i get pregnant on my period?i took pregancy tests two weeks after each guy.they came out negative then on June 13th i had unprotected sex with guy number 3 then June 20th i had a doctors appointment and i did another pregnancy test it came out negative.July 3rd i had sex with guy Number3 again then on july 7th my test came out positive.did i get pregnant on my period? or did i get pregnant from guy number3? my conception says between june 8th and the 13th.