If these are definitely correct, only then can we conclude that your lactation is insufficient. A full milk supply is not usually reached for several weeks, and by 6 weeks the adequacy of milk supply will be demonstrated. If the baby fails to start gaining weight or later fails to maintain an adequate weight gain, then partial supplementary feeding must be started. There are many women who successfully combine breastfeeding with supplementary feeding, and continue in this way for many months. Supplements are usually given after the breastfeed.
Some mothers find they only have to give one or two small supplements a day.
Other mothers find they need to give one after every breastfeed. It depends on your breast milk production. Mothers usually find they plateau-out at a certain level of supplements. But to avoid this potential problem, supplements can easily be given to the baby by cup. Any small cup with a smooth lip or edge will be suitable e.g. a medicine measure.