Breast to cup

Phoebe is 7 months old and has never liked a bottle.

I am thinking about switching to formula but think putting it in her sippy cup might work better. She loves her sippy cup!

I dont sterilise her sippy cup currently as was told by health visitor there was no need to after 6 months but would I need to sterilise it if I was using it for formula milk.

Also is there any difference between the different formulas? They all look the same to me!

And how often should I give her milk and how much?

Thanks!