My 6 week old feeds well at the breast but we have just started to introduce bottles (expressed breast milk) as I will be going back to work in a few weeks time. However, she takes the first 30ml/1 oz fine and then screams. It takes ages for her to go back onto the bottle and then she will only take another 30ml/1oz before stopping completely. It’s my husband who is feeding her the bottles, so I can express. What are we doing wrong?!