Is my newborn really being fed too much?

I just went to my sons 2 weeks dr apt and the dr told me that he has gain to much weight. he was 7 lbs 14 oz at birth and now 9 lbs. hes fed and im feeding him like im suppose to every 2 hrs and he tends to fed on both sides during the feeding. his dr said that is fine but at the same time said hes eating to much. so now im worried that im feeding too much so ive only been feeding him from one side each feeding since talking to dr. oh and his dr told me to give him a pacifier between feedings saying that hes not hungry just wants to suck on something. but how do i tell if hes really hungry or just needs to suck on something. I don't want to over feed him but i also want him to get enough as well. so whats the best way to tell the difference between hungry and wanting to suck on something. and can it just be in his genes to be growing big (his dad was 10 lbs when he was born)