Formula /solids

My 4 1/2 month lo has not increased her formula she is at 6oz evert 3 hours but doesn’t always finish the 6. My doctor said not to start solids until she’s reached 32 ounces which is definitely not happening.I’m finding that she’s getting hungrier quicker but when I feed her the bottle she doesn’t even finish it I’m really thinking about starting solids she’ll be 5 months in a week. I’m hoping this will satisfy her better

has anyone had this experience before