Foormula fed babies should be on a 3 hour routine at 10 weeks, to move to longer routines babies need to be able to do longer A times and the 4 hour EASY is not until about 4 mon ths. That said, formula fed babies do sometimes need to move to longer feed intervals sooner but it makes EASY really messy because they aren't able to do the A times.
You could try her on a 3.5 hour EASY and see if that helps the feeds, you will have to do something like EASAE to make sure she doesn't get OT though and watch you don't feed to sleep if E comes right before S!
HTH!
Laura