6.5 mth old DD is formula fed and uses nuk latex teats. She was ebf until a mth ago and these are the only teats she'll use. Have tried using silicone nuk and tommee tippee bottles (as have loads from last dc) and she won't bother. Problem is we're using a medium teat for 6-18mths and she's collapsing them and getting frustrated at slow flow. She's also drinking less as I guess can't be bothered?! Any ideas what teat we could move to?