conception date

[eleb82]

hello,
i need some help estabilishing a more accurate conception date.
i had sex with a man around the end of march, like march 25 or 26 , he did not come inside of me, we ended up finishing with oral sex, thats how he came.
then my period came a little late, like 5 days late, and also found out through a ultrasound i had an ovarian cyst. (that went away with my period though.)
just to be sure, i took pregnancy tests and they were all negative then.
so my period came around april 3rd, and lasted like 4 days, like it has always been though.
then around april 9 i had oral sex, no penetration at all.
from april 13th on i started having unprotected sex with my boyfriend .
on may 17th i found out i was pregnant, and the same day i had an ultrasound that was stating i was 6 weeks and 3 days pregnant and the due date was january 7th ,2013.
the other ultrasounds i had were stating that my due date was on january 10th, ( morphologic ultrasound i had at 20 weeks, and a 3d one that i had at 25 weeks)
i need to know when i have conceived. my doctor says sometimes around april 16th.
i need to know if there is a chance that i got pregnant , maybe with pre ejaculation sperm, at the end of march,and maybe what i thought it was my period, was only implantation blood?

if so, though, all the ultrasounds i had should have stated that i was 2 weeks ahead, right? please answer me, im very anxious!
im 34 weeks .

[WiggleWiggleWiggle]

For a doc advice post ur question into the doc forums. The ultra sounds r not totally acurate and the due date is only an estimated one.

[eleb82]

my bad, thought i could also get a doctor advice.

[stefani2013]

Bump your question, reposting is against medhelps rules.

[erikamtz]

to me it sounds like its your bf's .