Breastfeeding choice

I feel like everytime i need to defend my choice of breastfeeding and not supplementing with formula. My baby was born 6 lb and 9oz and he been of small build. He is exclusively breastmilk fed and he was gaini g weight at his own pace. Doctor was happy with his growth chart. However all our friends suugest us to give him formula just to help him gain weight.. i am able to meet my sons milk demand and feeding him breastmilk.. i feel like judged for breastfeeding ..i respect mothers who chose to formula feed their kid but i am really tired of hearing people comment and making me feel that since i m not giving him formula .. my kid is getting WEAK.. yeah thats what they say weak.. my son is very active and nicely meeting all his milestones.. m not sure how to give back 😕😬