Top feeds cater to meeting the basic nutritional needs of your baby. Of course there are some biological components in breast milk that won’t be available in the top feeds but worrying about it will not solve matters. Once you have sorted out your health issues try to establish lactation with the help of your lactation consultant and try and remain positive. There are lots of babies on exclusive formula milk who do absolutely fine too. Once you start solids for your son after 6months ensure nutritious food intake to ensure good immunity. All the best!!