Baby refusing bottle, throwing out so much milk

We neglected giving our baby a bottle regularly and now she is almost 5 months and refusing it when we try. Daycare and work starts in a few weeks so I am a bit worried.

I am sick of throwing away so much of my milk :(

Considering switching to formula for bottles, until she drinks properly, and building up a stash for when it goes better.

Anyone else have similar troubles or any advice for me?

The few times she does take it, she drinks very little and makes a mess.