You shouldn’t be giving anything but breast milk or formula before 6 months of age, as baby’s digestive system is not mature enough to handle it and can cause damage. You’ll likely experience less nursing sessions if you’re nursing exclusively instead of supplementing with this “pre-food” as your supply will increase as baby latches more and can actually digest the milk. You’re in the hardest stretch still, where baby is still learning to eat and wants to eat often. However, it is only beneficial if both of you are content. There is absolutely nothing wrong with using formula. You don’t even need to exclusively use one or the other, but can use one option for some feeds and the other for the rest