is perfectly normal as per your gestational age
You have to follow your EDD as per your LMP if you are sure of it and not according to your ultrasounds.
If your lmp is 12th jan, then your EDD is 19th october 2012. This means that you would be 40weeks on 19th october. Delivery can occur on this date or a week before or later. Any delivery after 37weeks is safe and considered term delivery.
Grading of placenta is used to assess the maturity(age) of placenta but doesnot have much significance except in pregnancies with fetal growth restriction, or hypertension
. Since you dont have any of these , you neednt take grading into much consideration. Its role in outcome of pregnancy
is yet to be clearly defined.
Chances of normal delivery depends on many factors. If your baby's head remains down ie cephalic position then only you given trial of normal delivery. Success of normal delivery depends on other factors like pelvic space, if any cephalopelvic disproportion present( baby size disproportionate to pelvic space) , progress of labour in terms of dilatation of cervix
and descent of head of baby.
If all these remain favourable, you would deliver normally.
For now you can deliver normally and as such there is no indication for you to go for a cesarean as per your scan. I dont know about your pelvis adequacy though it should be adequate as your baby size is not too big( when 4kg). If there is previous history of cesarean section then chances of normal delivery decreases though its not contraindicated (only when two or more cesarean).
Hope you delivery safely be it a normal delivery or a cesarean,