Hey Janette, I hope you get some good suggestions. I'm crossing my fingers for you. Unfortunately, I was not able to successfully make the switch from pre-made to powder until my daughter was much older. I tried several times, waited a month or so in between attempts, but she hated the powder type. I wasn't able to make the switch until she was over 12 months and her pediatrician wanted her on 'toddler formula', which only comes in powder (e.g., she lost weight soon after introducing milk--turns out she was allergic to milk... but that's a whole other story!!)
Ultimately I thought that the powder type might taste grittier than pre-made and perhaps that is why she refused it.
aha, I just remembered something... I was able to get her to consume a whole sample cannister of powder formula that we were given from our pedi. Of course, after she finished that and I bought the bigger $20 version, she then refused it. I was so disappointed... and of course her daycare was a bit stressed out that she wouldn't eat and kept crying, so that also prompted me to switch back to pre-made.
You might want to try mixing the premade with powder 1oz at a time, see if she'll take that for a week or 10 days, increase to 2 oz, wait... then 3 oz, etc.