Best organic formula for preemies

My boy was born on Friday at 36 weeks weighing 4.11 lbs (now holding steady at 4.5). Due to me having severe preeclampsia my liquids are limited to 100 ml an hour so producing much breast milk is a challenge. Also he's little so they want him to pack on the pounds. I'm giving him simulac neosure provided here at the hospital but I hate it bc it's not organic and mainly corn syrup. I don't feel it's healthy enough for him even if he is maintaining his weight. I want a healthier option until my breast milk comes in fully (right now he's getting about 5-6ml breast milk per feeding and 15-20 ml formula). Does anyone have any suggestions?  I'll see what my pediatrician says when we see him once we get released but am curious what other mommies are doing.