Any tips on how to wean her? I've tried before, and nothing is working.

When my son was nearing 3 years old, my wife decided that she didn't want to
do the quick morning and night breast feedings any more (which were really
for comfort, not for nourishment). For about 6 weeks before his birthday,
we talked about how when he was 3, he would be able to do more things, be
bigger, be taller, but 3 year-olds no longer got "mommy milk". He never
questioned it since we were so low-key about it. The last time was the
morning before his birthday party, and although he politely asked a few
times after that, he accepted it without any tears or argument.

I know you asked about bottles, not breast-feeding, but it might work just
fine.