I am using Tommee Tippee Closer To Nature bottles for EBM when I need to give DD a bottle now and then. I have been using the newborn teats. Now she is four months old should I use the next size teat (labeled from 3 months), or should I stick with the newborn, as I don't want her finding the bottle really easy and rejecting the breast. She drains her bottle quickly, and doesn't seem frustrated. Any advice really greatfully received!