Sorry, me again! LO is on prescription formula and I'm keen not to waste any, but she seems to want more than the guidelines. How do you know how much to make up? Without making far to much and yet making enough so you dont have to make an additional 1oz just to top up? Do you just guess to start with? I'm currently mixing EBM with the formula so don't want to waste that either! Also, how many bottles do you have? I have 3, is that enough? How do you know when to go up a teat size? Do you pre-boil your water and leave of ready in the bottles so you just have to add powder? Or do you boil it ready each time? Is it really bad to microwave heat the milk?