ALl the dates match exactly so there is no way it can be the other persons.
Had scan and they gave me my due date as 26th January, and I slept with my boyfriend on the 4/5/6 May - the other person was on the 18th April and I then had a period so I wouldnt have overlated. Thanks for all your kind emails - I wont be sleeping around EVER again.
Your Input
Last period started on Apr-21-2008.
Number of cycle days is 28.
Result
Your next ovulation will most likely occur on Monday, May-05-2008.
Your fertile days are between Friday, May-02-2008 and Wednesday, May-07-2008.
If you get pregnant during this cycle, your due day would be Monday, Jan-26-2009.