Low weight for 7 month old

My little guy was 9.8lbs when he was born. We went in for a check up and he is now 14lbs. They gave me a list of things to do to help him gain. Nothing is working, then within 20 hours he had 8 dark dark brown diapers and full. I called his doctor... ok maybe we are giving him to much.

He is breastfeeding on demand. Eating baby food with oatmeal twice a day. Went diapers, was only pooping once a week. 3 weeks ago, I was basically told that I'm not feeding him as well as I should. Then with their help he basically pooped all day.

He is happy, hasn't been sick, sitting, smiling, trying to stand, loves to talk and loves his family.