38 weeks measuring at 45

Has anyone else been in for a growth scan in which They’ve been measuring way over? Been in today as since 32 weeks I’ve been having fortnightly growth scans as I was measuring on the 35th percentile and each scan I’ve had accelerated growth to now measuring big. Well today I’m measuring on the 105th percentile and they won’t do anything about it other than another scan in 2 weeks to see if she’s still gaining about a pound and a half a week, making me 40 weeks + 3. I’m fed up and if she continues at the same growth rate she’ll be 12 pounds in two weeks!! Im not very big myself, I feel fed up and I’m scared they’re going to have to do a C section and I really wanted a natural birth if possible :(