Pregnancy

[Jackyb89]

I have a problem that has been worrying me about my pregnancy. I was single at the time of conception and had intercourse with man A on January 31st. I have written on my period calendar that I had my period feb 6th however I still for some reason question if I had it just because I'm being a worry wart. On February 28th a month later I had sex with man B. About six weeks later I took a pregnancy test and it was positive. On April 14th I had an ultrasound and they pushed my due date 11/12/16 from LMP to 11/19/16 because I was measuring small at 8weeks and 5 days. I feel like all of the facts are there that man B is the father, as I have told him and I don't see how it would make sense that man A is the father. Is there any way the ultrasound could be 3 or even more weeks off? Hello I can't stop worrying.