help !

I'm breast feeding and supplementing with formula because of my low milk supply . Anyways i have gone through three different formulas and 6 different dottles to help with her gassy belly. I saw a doctor 4 days ago and he gave us gentlease . My baby is still gassy and crys during feedings. I switch to the playtex drop ins and I elimante all of the air before I feed and I also give her gas drops ( gripe water didn't help ) . Is there any formulas that help your little ones in the same situation? I've tried soy milk and the regular infant formula .