yes - do you know when you ovulated? Counting 38 weeks from ovulation is more accurate than counting 40 weeks from lmp - as most women (especially breastfeeding) do not have exactly 14 days (2 weeks) between lmp date and ovulation date. My midwife recommended against getting a dating scan with my last pregnancy, as I knew the exact date of ovulation, and she said that this was more accurate than the lmp and scan combined.

I think its probably a positive thing that your scan date is after your lmp date anyways - as this means there will be less pressure on you to induce if you go post EDD - which we all know is just an estimate at best anyways. Scan dates change (are usually brought forward) with each successive scan - so you will probably find they get closer to your lmp date with each scan anyways.
The innate wisdom of Mother Nature, your body, and the baby combined is a trillion times more knowledgable about when labour should start then all the medical professionals in the world combined. Unless of course there is a serious medical reason for intervening, birth is always safest when left to nature. The baby, your body and mother nature couldn't care less about arbitrary timetables set by external doctors or medical scanning equipment. Birth is a spiritual event and sometimes i think the powers that be purposely avoid the 'due date' just to remind everyone whos boss - iykwim? The true incidence of placenta breakdown is EXREMELY rare - many women end up with unessessary interventions because of scaremongering about this rare condition.
Having given birth before - I think you can rest assured that your body especially knows when the right time to birth is this time, and will get the ball rolling when mother nature gives the cue. Its not possible for anyone to know the true due date so just roll with it and enjoy the ride - and most importantly -
Trust in your body!!
XXX