hi, i just want to ask about my pregnancy.. 

im about 26 weeks pregnant base on my first ultrasound.. and 27 weeks if i base on my LMP my doctor said she base on my first ultrasound scan not on my LMP.. so my due date is on april 8 2018, but my AUA said my due is on march 31 2018, where do i go? and is there a possibility that i conceived july 16 3 weeks before my period start again?. (sorry for my bad english) please help