Hi there
You don't have to introduce a bottle at all, unless you want to. It is perfectly fine to use a sippy for EBM, and it's often recommended to do this rather than the bottle if introducing EBM after 6mos. Also, at least in the UK, they recommend to ideally switch from bottle to cup anyway at one yr old. At one year old you can give cow's milk in a cup if you don't continue to BF and she will also be able to get her calcium and other nutrients from a good varied diet. So there's no need to introduce a bottle, however some mothers prefer to use a bottle even at an older age due to it being "less messy", some babies take more milk from a bottle than from a cup (but that really depends on the baby) or for other reasons. From my own experience with DD1, a bottle *can* also interfer with BF as it is easier to get milk from it and the flow is always steady and the same, comes straight away etc, whereas with the breast they have to work for the milk, wait for the letdown, flow changes throughout feed etc. Bottle preference doesn't always happen, and many mothers and babies combine bottles and BF just fine, but it is a risk that is always there when you introduce a bottle to a BF baby, and a very good one to be aware of in my experience. DD1 developed a bottle preference which led to supply problems and eventually premature weaning, but at the time I didn't know anything about this and had no support, but I really wish I had known where to get support to help me with it so we could have carried on a bit longer. Not wanting to scare you or anyone else with this, that's not the intention
but just to let you know there *are* some risks if you do introduce a bottle, and in your case it just doesn't seem worth taking those risks as you don't have to
HTH and let us know if you have any further questions