Conception calculator gives the following:
First day of last menstrual period: July 30, 2012
Probable date of ovulation: August 13, 2012
Possible dates of conception: August 9 to August 17, 2012
Due date: May 6, 2013 (40 weeks)
If your estimated due date of May 6th was given to you by an ultrasound, your ex is not the dad. If it was just counted out on a calendar, it wouldn't hurt to get an ultrasound to confirm.
Do u kno when u were ovulating???