Confusion with dates

[Leirope]

My LMP was 26/8/15 and my cycle has always been irregular, averaging out at about 35-45 days long. When I went for my first scan I should have been 10 weeks based on LMP, but little one was measuring 8 weeks. When we went back for our next scan, two weeks later, he had grown by two weeks, so doctor reassured us that owing to the discrepancy in the length of my cycle I was 10 weeks (not 12 weeks as it should have been by that point).
So at this point I should be 29weeks. I just had another scan today (I'm in Greece atm where they do one every month) and was measuring 31 weeks, which tallies with my LMP. Doctor has revised my due date (eek!) two weeks forward, but I'm sure I've read elsewhere that you should stick with the earlier estimates as they are usually more accurate.
I'm planning on coming back to the UK for the birth and seeing the midwife for my first appointment next week so will ask her for clarification then, but just wanted to see if anyone had any thoughts on whether I'm 29 or 31 weeks?
Thanks in advance

The earlier scans are far more accurate and here they'll use your 12 week scan date. Regardless, the baby will come when it's ready!

That's what I thought, but the doctor was adamant for the later week. Ah well, he'll come when he comes!

It's basically all guesswork! You'll know when the baby wants out, don't you worry

Early scan dates are definitely more accurate.
I've had ivf so know my dates exactly. Scan at 7 weeks tallied up. By 12 weeks it was measuring 12+6. At 19 weeks measured 20. And at later growth scans measures 5 days to 5 weeks ahead depending on what measurement they are taking.

Also, the 12 week scan date will be based on crown to rump length where as later scans post 20 weeks will be based on femur length, abdomen circumference and head circumference.

So basically my baby just has big bonce? Must take after his daddy...