Hi, Food and water (as well as, importantly breastmilk) are the main game here. If baby needs more she will breastfeed more or eat more food. It's not necessary for her to have formula or soy milk. Do you offer water? If you wean onto a bottle, then one day in the not distant future you will have to wean her off that. Soy milk will be OK as a drink, but it wouldn't suit as a replacement for breastmilk (but then again she doesn't need a replacement for breastmilk) She needs around 600mls of milk per day and this can include breastmilk, which will make up the bulk, cheese, yoghurt, custard etc. Giving her her milk requirements as food will generally allow her to continue to breastfeed for longer.