When we first introduced a bottle, at 4 weeks, she would take anything and had no problems going back & forth. We took a break, and when we tried again around 3 months she refused everything except the Tommee Tippee.
I use the Vent-Aire System. They have special, wide nipples to help with the transition to using a bottle. It simulates the breast better than normal nipples.
BreastFlow from 1st years. It mimicks a regular milk flow and makes my dd work for the milk. Also it is the right size and feels like a breast. Good Luck!
Re: what bottle do you use for DD when you are not nursing?
THIS
In my bag: Canon 60D, 50mm 1.4, Tamron 28-75 2.8, 430exii
Levi 4.21.10