my love i am in the same problem!!!! with very close dates to you also!!
i can'tremember my last period date and i slept with my boyfriend on the 3rd 4th and 10th april we then broke up and somewhere between the 25th april and the 3rd may i had sex with man 2* i have been given the 14th jan for my due date and had 2 scans one on the 13th june which said i was 9 weeks and another on the 7th july which said i was 12 weeks 5 days i was very worried about this and did talk to my midwife who explined that when your scan dates you it tells you how long the baby has been growing there for dating you from conception not your last period. your scan date can be out by 6 days but in early scans it is very unlikely to be out by anymore that 6 days.
your midwife is there to help and wont judge you talk to them you'll really know where you stand then.
my boyfriend is most likely to be the father but we have both decided to have a dna test when the baby is born to be sure.
hope this helps and i hope you are enjoying being pregnant again xx