Lactation Consultant or Pediatrician

I’m sorry if this is rude but I wanted to ask how credible are lactation consultant’s? I visited one for the first time today and while there we discussed baby’s weight. Baby is 2 and half months old but he was born prematurely so his adjusted age is about 1 month. He was born at 5lbs 2oz and now weighs 11lb 4oz. His diet is mainly breast milk with 2 teaspoons of formula a day. His pediatrician said that I only have to fortify his formula until he is 4 months old unless he starts gaining too much weight. However, the lactation consultant said I can stop giving formula since he’s at a good weight now. I don’t see his pediatrician until another month so I’m wondering if I should listen to the lactation consultant or wait until his pediatrician says so?