Feeding problem

My baby girl is four months old.in the first 3 months she had severe colic . Thankfully it ended and i thought now i would get some break...some me time but now she resists milk...her intake is of a newborn...she sleeps poorly and on my lap and when she drinks ..she does so while i carry her and still feed very less.her average intake is 14 to 15 ounce in 24 hours.We have been to a lot of doctors...some say it is acid reflux but I don't know. We have changed her milk four times but the resistance persists.i am very worried that she is not feeding enough so i am trying to introduce solids although she is not of age because of her intake...i am loosing my mind because its a 24 hour duty.

Is anyone with a similar problem?plz share ❤️‍🩹