Getting a breastfed baby to take formula

Hey guys, so my 3 month old is EBF. We have a dinner Saturday night and I am leaving her with my mother from 5-9. Ideally id like to try and pump so she has breast milk but I’ve never really had too and the times that I tired I can’t get anything. I’m not even sure how much I would need to leave for her. If I’m not able to pump much is their a certain formula that breastfed babies like more than others? With my first he went to exclusively formula fed at 6 months due to bad reflux and other issues. It would just be for two feedings while I’m gone. What are your thoughts?

The formula will be a worst case scenario if I can’t pump enough by Saturday.

Let me know what has worked for you!

UPDATE: Thank you everyone for the advice! I tried a few of your tips and it actually really helped! It’s not a lot but it’s the most I’ve ever pumped in one sitting 💪🏼 thank you guys so much 😊