K.H.
The baby can be head down , and even engaged from quite early , my 2nd child was almost fully engaged from 32 wks and I was convinced I would have her early , however I went 6 days past my due date. Ultra sounds are pretty accurate , and if your U/S matched up with how many weeks along you were then I would say it is pretty certain that you are due when you think you are , yes baby could come early but who knows , and the due date is just a guess based on the first day of your last period , so no-one ever knows for sure exactly when baby was concieved.