The slower flow is often better for bfing babies as it encourages them to work harder for the milk, same as they would on the breast. The faster flowing teats tend to 'pour' the milk into baby's mouth, giving them not much option but to swallow quickly! If you are still bfing it's probably better she has to work harder for the EBM in the bottle so that she doesn't get frustrated back on the breast. How long does she take to finish a bf? You might be able to find a happy medium that seems to take her about the same time as a normal bf.