Even more guilt over formula

So to make matters worse, Easton doesn't tolerate formula well. I knew this already from the few times I had given him the little 2 oz. bottles of shelf stable formula they give at the hospital. He throws up everything for about 24 hours after he has it. No bueno. I talked to my pediatrician about it and he recommended that I try Enfamil Gentlease. I semi got over my guilt today and trekked off to Sam's Club tonight to get a HUGE can of formula. So I'm feeling experimental and I decide to give him just a few ounces tonight before bed to see how he does and see if formula fed babies really do sleep longer. I mixed a few ounces of breastmilk and a few ounces of formula to make a five ounce bottle. A few ounces in, he puked all over me. Great, huh? Serves me right? I'm hoping it was partially because he was too full because it wasn't time for a feeding yet. I was reading about it online and it seems that you need to give the baby atleast a week with each formula to really try it out before switching again-- even if they are puking all over the place. So now my poor little Easto has to vomit all day just so that I don't have to pump. Talk about a major guilt trip. I'm going to keep at it though and just really ease him into it with more breastmilk mixed with the formula. Poor little guy......