Late Period & Possible Pregnancy: Understanding Cycle Irregularities

Question
I AM 26YRS.OLD WITH FOUR CHILDREN,I CANT REMEMBER IF MY PERIOD CAME ON THE 5TH OR THE 9TH OF JUNE BUT MY CYLCE STAYS ON ABOUT FIVE DAYS.MY QUESTION TO YOU IS IF I HAD A PERIOD IN THE MONTH OF MAY COULD I BE PREGANT AND MY PERIOD BE LATE IN THE MONTH OF JUNE BUT STILL HAVE A CYCLE IN JUNE.BECAUSE I FOUND OUT THE I WAS PREGANT IN JULY 2004 AND I DID NOT KNOW WHEN MY LAST CYCLE WAS SO MY DOCTOR DID AN ULTRASOUND AND IT SHOWED THAT I WAS 9WEEKS 4 DAYS AND THAT MY DUE DATE WAS MARCH 20TH.I NEED TO KNOW ARE ULTRASOUNDS ALWAYS RIGHT.I HAD SEX WITH TWO GUYS AND I THINK I KNOW WHO IT IS DUE TO MY DUE DATE AND THE DOCTOR TOLD ME THAT BECAUSE OF THE ULTRASOUND I HAD TO HAVE GOTTEN PREGANT AROUND THE JUNE 25-27TH BOTH GUYS KNOW ABOUT EACH OTHER BUT I WAS WITH THE FIRST GUY FOR ABOUT 5MONTHS AND I NEVER GOT PREGANT BUT WHEN I GOT WITH THE SECOND GUY I GOT PREGANT .WITH THE SECOND GUY WE USED A CONDOM SOMETIMES BUT HE SAID THAT HE NEVER CAME IN ME.BUT WHEN I TOLD HIM THAT I WAS PREGANT HE NEVER SAID THAT HE WAS NOT HER FATHER HE JUST WANTED A DNA TEST  PLUS HE SAID WHEN I TOLD HIM THAT I WAS GOING TO GIVE HER UP HE SAID WHY GIVE HER TO ME .BUT I WAS THINKING IF WE USED A CONDOM AND HE DID NOT DO ANYTHING TO IT WHY WOULD HE WANT A TEST AND WHY WOULD HE TAKE A CHILD THATS NOT HIS.PLEASE HELP ME BECAUSE I DONT HAVE THE MONEY TO GET A TEST DONE AND I HAVE NEVER BEEN IN THIS BEFORE AND I DO BELIEVE THAT BY THE ULTRASOUND AND MY DUE DATE THAT THE SECOND GUY IS HER FATHER .MY DUE DATE WAS THE 20TH OF MARCH SHE CAME THE 19TH.ALSO I WAS THINKING THAT SINCE THE ULTRASOUND WAS RIGHT ABOUT HER BEING A GIRL THAT MAYBE IT COULD BE RIGHT ABOUT MY DUE DATE.BUT COULD I BE WRONG AND THE DOCTORS TOO.PLEASE HELP ME
THANKS.

Answer
You claim that your period started on the 5th or 9th of June, but we have not reached June 5th yet, so I don't understand what you are saying.  You doctor is correct. If a sonogram showed that you were due on March 20, you definitely conceived on June 25 and your last period started on June 12. You could have become pregnant if you had sex on June 24, 25,26, or 27. I do not know who you had sex wth on those days. If there is any doubt, I would suggest paternity tests. If you know who you had intercourse with between June 24-27 then you don't need paternity tests. If you have a period in May, you ovulate around 14 days after the first day of your period. A pregnancy test will not show a positive result until 14-21 days after the date of conception.