Baby Weight at 34 weeks

At 34 weeks, how much is baby expected to weigh? I had an ultrasound today and DR told me that baby is about 6lbs and she estimates that his weight at birth will be 7-8 lbs. I asked her if he was over weight and she said no that his weight was fine. My first son was born at 6 lbs 1 oz and I know that baby # 2 isn't going to weigh the same as #1  I was just kinda freaking out because 6lbs sounds like alot, although she said his weight was fine.