I tried everything to get my little guy to come with my first pregnancy. Nothing really worked he came a week late when he was ready. I do have a friend who has had 3_ 10lb babies and she said she had no problem having any of them. So i think the best thing you could do is just wait they will come when their ready. I'm sure if there were any problems with your baby being to big to deliver your dr. Would do what they felt was best for both of you.
Ultrasound are just am estimate and very rarely exactly accurate in determining the weight however from experience sex helps to induce, not the sex but the sperm, helps bring on contractions. Good luck!