Best formula for switching from breastmilk?

Welp. The time has come. I made it almost 4 months but i just cannot continue to breastfeed this child full time. She doesnt want to latch and i am not pumping enough to feed her. She needs her lip and tongue tie revised and i know that will help things but the dr i would go to wants payment upfront (insurance will reimburse) and i just dont have $600 extra.

Whats the best formula and/or way to transition from breastmilk to formula? Im hoping i can pump and store some milk to give her and in still going to try to nurse her, but i am exhausted. Ive been fighting her for 3 weeks and its time to give.