this has only just dawned on me following some reading, and a comment from a friend. DD2 is 12 weeks old and excl bf. should i be feeding from both breasts at each feed? she has always just fed from one, and feeds for about 10 minutes. she is growing well and feeds about every 2-3 hours during the day, and 3 - 4 hours at night. But am i doing something that will be detrimental?