i always used regular powder. but you store the breast milk and them make a little formula when you need it. its not good to store after mixing. i use baby water or nusery water. especially when little. 2oz of water for every scoop of formula. so i always found it easier to make a 4 oz just makes it easier

You can buy it at the grocery store or walmart. I don't use tap water. It's a gallon jug of baby water. There's nursery brand, parents choice or gerber brand. It's like $1 a gallon.

I wouldn't mix them. Formula is only good for an hour after the baby has drank from it. Breastmilk is good for much longer. If she doesn't finish the bottle then you're wasting

What's nursery water? @jacesterlingsmommy

That's how I always did it. I used nursery water and made formula just like normal then added he BM.