Introducing formula to a BF fed baby - need help

My DD is 3 1/2 months old and has been exclusively breast fed until now.

I am introducing formula - Gentle ease - and was doing it by mixing a 50 - 50 solution of formula and expressed breast milk.

I talked to my ped who suggested sticking to one bottle of formula. He said this for digestive reasons (breast milk is digested faster than formula and he wants me to wait 4 hours between feedings for formula)

But I am so confused.

Which feeding should I start with?

How many oz of formula for 15lb baby?

Any overall advice>

I feel like a bad mommy. I really don't know why but I just feel like I have NO CLUE what I am doing lately. She isn't sleeping at night well anymore , she cries often and seems like she is in pain (even before I introduced the formula) and I just feel like even a simple thing like introducing a bottle of formula is complicated!!!

Re: Introducing formula to a BF fed baby - need help

Don't beat yourself up!! Introducing formula to a baby is NOT always a simple thing. In my experience, it was QUITE difficult. It took me 2 months to find the right formula for her.

I started with her 12:00 feeding. One bottle for 2 days, then 2 bottles for 2 days until she was completely on formula. It took me 2 weeks. Even then, I had to cut her formula with breastmilk for a week afterwards.

I gave her 4oz per bottle. Your baby will tell you if that's not enough by crying for more when the bottle is empty!

It takes time, patience, and a lot of trial and error. Hang in there!