Adding formula-help!

My daughter is 5 months and has been EBF since the beginning. I exclusively pump but recently went back to work and due to stress and just life happening, I’ve been struggling to keep up with her needs. She usually eats 4oz at a time and eats 24-28oz per day, sometimes a little more. The past few weeks I’ve been struggling to pump 24oz max, so I’ve been using some of my freezer stash to supplement on days that she eats more than I make. I’m ok with probably having to supplement some formula soon, I’m just totally clueless on the “best” or “right” way to go about it. I’m still going to keep pumping so she will probably only need 4-8ish oz extra. But, would it be better to do a full formula bottle for a feeding or to do a feeding with half formula and half breastmilk? Or does it even matter at all? If I do a full formula feeding, should I feed her the same amount that she normally takes of breastmilk (about 4oz) or will she need more formula? Also, if you have any formula suggestions that you like better than others, I’d appreciate that too.

I know I’m over thinking all of this, but it’s kind of what I do. And I’m gonna stress out about figuring out how to do both until the time comes that I have to. 😅