Could you tell me what you would do please? hard to explain in title. but about formula and 8month old.?

I would speak to her pediatrican again. The extra water when she was younger is a good fix for constipation. However, after 6 months of age, it is acceptiable for babies to have small amounts of juice (preferrably, this would be when a sippy cup is first introduced). Maybe instead of all the extra water now, a couple ounces of prune or pear juice a day would be a good option? If you are comfortable with the water only, perhaps making her bottle as instructed on the can, and giving her the "extra water" (10ml per scoop), seperatly as a few sips all throughout the day. So if she takes 3, 8oz (240ml) bottles a day, she should be getting an extra 4 oz of water per day (40ml X 3= 120ml = 4 ounces)....try just offering those 4 ounces of extra water seperatly in it's own bottle for her to just "sip" out of throughout the day. Or just break it up into 2, 2oz bottles of plain water (this is what I did with my son as an infant). My son was on soy formula and had bad constipation issues as well. I always made his formula as directed on the can, and then twice a day I would give him a 2 ounce bottle of plain water between his formula feedings. Best of luck.