I think that the amount of caffeine in green tea is low enough that it shouldn't harm your baby while breastfeeding. I know plently of bfing mamas who even drink coffee(in moderation) with no apparent effect on their nurslings. I drink 2-3 cups of green or black tea every day and I don't think it affects my ds in any way. I agree, red tea is delicious! As for herbal teas, I know that peppermint is reputed to help when you have oversupply issues, so I would probably not drink a lot of peppermint tea.