Gentle ease and newborn formulas?

I was breast feeding and started supplementing with enfimil newborn formula....baby has always appeared to be gassy since birth.... So I switched to gentle ease....things were going better but I discovered she appeared more gassy and fussy when I gave her my pumped breast milk along with the gentle ease. Just one bottle of breast milk a day seemed to make her more fussy! So I give just formula now. She's doing OK with gas on the gentle ease but it seems it doesn't fill her up. She will take 3-4oz every 2 hours during the day.... And we are up every 1.5 hours at night. She is one month old. Is that still normal at 1 month???? Or is the something less filling in the gentle ease as opposed to newborn formula?? If so should I mix the two so she gets filled up a little better and eventually switch her back to the newborn since I believe the breast milk made her fussy not the newborn?