measuring large

Hi, my due date is Labor day, but I went in today and the dr. said that the baby was “humongous” he’s a funny guy, so I just thought he was joking, becuase he didn’t say anything else. But, my mom works at the hospital and sees him sometimes, and he told her that it was really big and that he wanted to do an ultrasound. ( which makes me mad that he’s talking about it with anyone, even if it is my mom, I’m an adult(23) and can handle an adult conversation) this is the first time I’ve heard anything about it. I’ve been growing normally, at the best to my knowledge, throughout the pregnancy. I don’t have gestational diabetes, and although I was a little “thick” when I concieved I was not obese, and have gained on the higher end of the normal weight gain charts. Although I don’t eat perfectly, I do try to keep an eye on it. Is this normal? has anyone had this? my mother swears it’s becuase of my diet, and that I’m somehow being “abusive” by eating my way to complications. I keep trying to tell her that there are other reasons for this, but she won’t have it. I have a feeling that my due date was off, but I can’t be sure. any advice? my next appointment is the end of next week.