Ultrasound due date is june 16th! any chance that protected sex on october 5th got me pregnant?

Not Really: In order for you to have a baby on or about sunday, june 16, 2013, you would need to have conceived on approximately sunday, september 23, 2012. Also if you had protected sex then by definition you could not get pregnant.

U should have: Conceived about 9/24 or 9/25 if your cycles are every 28 days if your cycles are longer than it is possible but not probable for 10/5.