My 3 month old will not!

My 3 month old will not eat more then 2 oz every 2 hours. She was in the 28th percentile for weight last time she went and the doctor said something about her eating so we have her on reflux meds for it and it seemed to help a little sometimes she’ll eat a random 3oz bottle. She also will eat 2 oz then want another another 1 oz after an hour. Mainly she just eats 2 oz every 2 hours. I changed nipples speeds I just don’t know what to do. I never push her to eat more then she wants to but it makes me want to cry and I’m super nervous. If you can’t tell I’m a FTM . Any one experience this with their baby? It makes me feel like a horrible mom. She has to be on soy formula because she has issues with lactose. If you could pray for her I know their worse things in life that could happen but I know I’m not wrong asking for prayer.