Now that we are approaching 9 months, i feel like i need to prepare myself (and LO) before going back to work in 3 months.

I am a bit confused with the whole weaning process, and i feel a bit stupid for even asking. But from 9-12 months, how much breastmilk/formula should babies be getting? LO eats 3 solid meals plus one snack a day, and i offer her the breast about 6x a day...only because her nursing sessions have always been really short. She hasn't been showing much interest nursing as often as before so i am assuming it is time to drop a feed. To those who were exclusively nursing, did you slowly start introducing bottles to wean? How long before they were only taking bottles?