HELP PLEASE

On July 29th i was with Guy A and the 31st i started bleeding it wasn’t a heavy period but lasted 4 days. On August 2nd i was wearing a tampon & took it out with no blood I was with Guy B and used no protection i was suppose to get my period again on August 30th but i was late and on September 5th i found out i was pregnant... would this baby be Guy A or Guy B. I am thinking of doing dna test when the baby comes. I am currently 13 weeks and 2 days pregnant.