My BB also on Mama milk, he is now 7 months old, but weights only 6.4 kg, however he looks healthy, and I never doubt mama milk, as this is the most nature thing to baby, and the most precious gift from God that a mother can give to her baby.
Flam1975, don't worry, as long as your BB is healthy, keep on with breastfeeding.
Do you know how the formula milk manufacturers find new "good" substance to add to the milk? They analyse breastmilk, and identify items that the formula milk don't have, e.g. DHA, NHA. . . , then make them/ extract them from various source and added to the formula.
Formula milk are from cow milk, cows do not have to develop their brain, so no or little DHA from cow milk. The manufacturers promote their milk added with DHA, but actually it is already in our breast milk. And there are a thousand substance not yet discovered by the scientists.