Hi ladies, I am a little confused and would lo...

Hi ladies, I am a little confused and would love some advice about BF. My little girl is 4 weeks old (but 6 weeks preemie) and I have always just fed her from one breast at each feed- alternating sides with each feed. However the community nurse mentioned I should be offering her both sides at each feed and I have also read this in a couple of books. I have tried this but by the time she has finished with one side she is not usually interested in the other side. Should I be trying to reduce the time she is on the first side and swap her over the other side after a certain amount of time (say 10 mins each side) or is there anyone who successfully feeds just from one side at each feed? thanks...