Re: 6 month old nursing for only few minutes at a time
How are your baby's diapers? If she's having enough wet and poopy diapers, then there's no need to worry: good diaper output = good milk input. Also, how often is she nursing per day?
Crazy nursing patterns around 6 months can be due to teething, which makes some babies reluctant to nurse, and also to development- the world is now so interesting that your baby may be forgetting to nurse. Try taking her into a quiet, darkened room when it's time to nurse- reducing distractions may make her feed more peacefully.
Is your baby getting any/many bottles? Sometimes a baby who gets a lot of bottles becomes lazy at the breast, in which case shelving the bottles for a while may help.
Keep offering! You can't offer too frequently. And keep your pump handy (if you have one). That way you can empty those plugged ducts even when your baby isn't nursing well.
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"