WIC has lost their mind!!!

My 5 month old had a WIC appointment last week where they weigh and measure him. He is 15.7lbs and 25 1/2 inches long. When he was born he was 5.6lbs and 20 inches. The lady put his info into their computer and then looked at me and said "you're not feeding him enough" of course I'm like say what.... He eats 7oz and eats about every 4-5hrs except at night because he sleeps all night through. I let him eat until he give the cues that he is done. I guess he needs to be fatter according to them. So at 5 months he has gained 5 inches and tripled his birth weight but I don't feed him enough apparently. I then told her that his doctor doesn't have a problem with his weight gain and said he is gaining good for how small he was. He also said that because he is more active and really trying to crawl that his weight gain might slow down a little bit. She then told me " your doctor is wrong, he is falling behind on his weight" Finally I was fed up and got mad and told her " well what do you want me to Do? force him to eat more? Would you like me to make him eat till he spits up? No, didn't think so! You are a nutritionist not a doctor and his Ped his no concerns with him at all. He has hit his development milestones just like he should, he has plenty of wet and a couple of poo diapers a day. His father is tall and thin, I am tall and was thin before I had babies. Have you ever thought that maybe he just won't be a "fat" baby. How dare you tell me that I'm not feeding him enough!" Its one thing to offer advice for weight gain but it's another to assume that I'm in some way hurting my child. This is also not the first time they have said stuff like this to me even though his growth has been consistent.