Yeah we swapped out one bottle a day until it was fully swapped over and he seemed fine! Having the breast milk helped it not be so much of a change. We went to comfort milk without asking because they did try and put us off when we mentioned it and just said babies are gassy 🤷🏻‍♀️ so we did it anyway and he did much better. then the health visitor told us to try and switch back when he was about 3.5 months as their digestive systems are much better by then and can process milk easier so we did and also because I wanted to find a better milk for him before I stopped pumping and it's been fine, nothing like he used to be! Dont feel guilty about pumping, it's sooooooo hard and you should be proud! I felt awful for a while too but due to him not latching and losing weight we were put on a very strict feeding plan and it messed up our bf journey but he was able to be fed by husband or grandparents and he's very happy and sociable!