Big baby? A rant...

So I went in for my monthly appointment around July 27th and since May I have been being told that I'm measuring "large". May was actually my 19w appointment, but I was measuring at 22 weeks. Well they measured me again last week and I'm supposed to be 29 weeks but measuring 32 weeks. Both with measuring my belly and the ultrasound. This is what's really bugging me is I could have very wel gotten pregnant before they think I did, I've always been super irregular and have had issues. But, instead the doctor insists that the baby is just large and it could be gestational diabetes. Which I tested for at week 27 and the results were negative, in fact I'm having a very healthy pregnancy. So I guess he wants to test me again for GD to prove that the baby is just large and schedule me for C-section. Because I guess having a normal birth would be "too traumatic"? I guess I just don't see why, I'm approximately 30 weeks (probably measuring at 33) and she's already flipped. She's not breech so I fail to see the "danger" in letting her come on her own, don't us mamas know our bodies? I'm a FTM so I'm open to other mamas opinions.