Pregnancy is confusing

At nearly 36 weeks I thought I had been really lucky in that I have had a pretty uneventful, straightforward pregnancy (so far). I was a bit confused by new things such as back ache and braxton hicks, but I figured, that's normal.
So when I was referred for an extra scan to check that the baby is growing properly. The doctor had noticed it was about 10mm too small when she measured it. To be honest I knew that there was nothing wrong but I like having scans so off we merrily went this afternoon for another scan. Terrifyingly the measurements came back that the baby is BIG for it's expected due date. All I can say is, I am now even more convinced that the due date was confused when I had that dating scan in February.
February is soooo long ago. Even back then I was sure the dates were a week or two out. Fingers crossed I am right though as the rough weight is estimated to be 6lb 8oz NOW!!! Still 4 weeks to go!!!! As soon as I hit my offical '37' week mark I am going to do all I can to get this baby out!!! I can't imagine having a giant baby. Makes me feel a bit squeamish, actually.