They said my baby is big! Worried

I went to the doctor last week and they said my baby measured on the big side. As in his head and chest are in the 80th percentile for growth but overall his body is in the 65th percentile which is a little big. I'm 29 weeks and he's already a whole 3 pounds. And I gained 4 pounds in 2weeks. When I got pregnant I was about 110lbs now I'm 145. Which I know is normal. I'm just worried about his size I eat a lot of fast food. And I may be small (except my belly) but I'm really out of shape. I know I need to eat healthier it's like nothing except fast food makes me wanna eat. I'm just worried I don't want him to be too big I still have about 11 weeks to go!