General Pregrancy

I found out I was pregnant on Monday April 18, 2016 and according to my period I would have been 5wks on the 19th when I went to the doctor but when they the ultrasound it was showing I was not 5wks. My period was 37 to 38 which came on March 15, 2015 so it would have put my period come the 21st or 22nd. My fertile time was supposed to be around the 2nd to the 11th with my ovulation around the 10th could it come early like around the 2nd