I didn't try to move mine from bottle to sippy cup or straw for milk until 12 months. I felt under 12 months he needed the comfort of the bottle but also the ability to guzzle it down efficiently. At 12 months I switched the BT milk to a sippy cup plus solids snack before the BT routine began and stopped his BT bottle, went very smoothly. But the morning bottle he was very resistant to, even though he was older than your LO. Despite him taking milk fine from a sippy for supper (although it was a small amount) he found it much harder to switch the morning bottle. After trying several times over that month he took a straw inside his bottle rather than the teat, I was then able to switch the bottle.
Initially I split the teat so he could sit up to drink rather than laying more backwards, but yk I think I discovered later that this is not advisable to split the teat, perhaps someone else has information on this. After that it was a few trials with the straw popped into his bottle before he took it. We used a wide disposable straw as that's what he would accept.
Maybe she's a bit young to switch all those feeds to a cup?
